Initial commit
This commit is contained in:
redclawsystems
@@ -0,0 +1,474 @@
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//! Fourier Neural Operator implementation.
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//!
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//! FNO learns operators by performing convolutions in Fourier space,
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//! enabling resolution-independent learning.
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use crate::{NeuralOpError, NeuralOperatorTrainer};
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use neuralop_studio_shared::{
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EvaluationMetrics, OperatorConfig, OperatorType, PDEDefinition, TrainingConfig,
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TrainingProgress, TrainingResult,
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};
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/// Fourier Neural Operator.
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#[derive(Debug)]
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pub struct FourierNeuralOperator {
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/// Configuration.
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config: OperatorConfig,
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/// Trained weights (simplified representation).
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weights: Vec<f64>,
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/// Is trained.
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is_trained: bool,
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/// RNG state.
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rng_state: u64,
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}
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impl FourierNeuralOperator {
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/// Create a new FNO.
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pub fn new(config: OperatorConfig) -> Self {
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let num_params = Self::calculate_params(&config);
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Self {
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config,
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weights: vec![0.0; num_params],
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is_trained: false,
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rng_state: 42,
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}
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}
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/// Calculate number of parameters.
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fn calculate_params(config: &OperatorConfig) -> usize {
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let hidden = config.hidden_dim;
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let layers = config.num_layers;
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let modes = config.fourier_modes.unwrap_or(12);
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// Lifting + spectral layers + projection
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let lifting = hidden * 2; // Input to hidden
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let spectral = layers * (modes * modes * hidden * 2 + hidden * hidden); // Complex weights
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let projection = hidden * 2; // Hidden to output
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lifting + spectral + projection
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}
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/// Initialize weights with Xavier initialization.
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fn initialize_weights(&mut self) {
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let num_weights = self.weights.len();
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let random_values: Vec<f64> = (0..num_weights)
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.map(|_| self.random_normal() * 0.01)
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.collect();
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for (weight, value) in self.weights.iter_mut().zip(random_values) {
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*weight = value;
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}
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}
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/// Simple random number generator.
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fn random(&mut self) -> f64 {
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self.rng_state = self
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.rng_state
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.wrapping_mul(6364136223846793005)
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.wrapping_add(1442695040888963407);
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(self.rng_state >> 11) as f64 / (1u64 << 53) as f64
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}
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/// Box-Muller for normal distribution.
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fn random_normal(&mut self) -> f64 {
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let u1 = self.random() + 1e-10;
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let u2 = self.random();
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(-2.0 * u1.ln()).sqrt() * (2.0 * std::f64::consts::PI * u2).cos()
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}
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/// Forward pass (simplified).
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fn forward(&self, input: &[f64]) -> Vec<f64> {
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// Simplified FNO forward pass
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// In reality, this would involve FFT operations
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let output_size = input.len();
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let mut output = vec![0.0; output_size];
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// Apply lifting
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let hidden_dim = self.config.hidden_dim;
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let scale = (hidden_dim as f64).sqrt().recip();
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for (i, out) in output.iter_mut().enumerate() {
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let mut sum = 0.0;
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for (j, &inp) in input.iter().enumerate().take(hidden_dim.min(input.len())) {
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let weight_idx = (i + j) % self.weights.len();
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sum += inp * self.weights[weight_idx] * scale;
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}
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*out = sum.tanh(); // Activation
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}
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output
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}
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/// Compute loss.
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fn compute_loss(&self, predictions: &[Vec<f64>], targets: &[Vec<f64>]) -> f64 {
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if predictions.is_empty() {
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return 0.0;
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}
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let mut total_loss = 0.0;
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for (pred, target) in predictions.iter().zip(targets.iter()) {
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let mse: f64 = pred
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.iter()
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.zip(target.iter())
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.map(|(p, t)| (p - t).powi(2))
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.sum::<f64>()
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/ pred.len() as f64;
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total_loss += mse;
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}
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total_loss / predictions.len() as f64
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}
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/// Gradient descent step.
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fn gradient_step(&mut self, learning_rate: f64) {
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// Simplified gradient update (random perturbation for demo)
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let num_weights = self.weights.len();
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let gradients: Vec<f64> = (0..num_weights)
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.map(|_| self.random_normal() * 0.01)
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.collect();
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for (weight, gradient) in self.weights.iter_mut().zip(gradients) {
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*weight -= learning_rate * gradient;
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}
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}
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}
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impl NeuralOperatorTrainer for FourierNeuralOperator {
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fn train(
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&mut self,
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pde: &PDEDefinition,
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config: &TrainingConfig,
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progress_callback: Option<Box<dyn Fn(TrainingProgress) + Send>>,
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) -> Result<TrainingResult, NeuralOpError> {
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self.rng_state = config.seed.unwrap_or(42);
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self.initialize_weights();
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let grid_size: usize = pde.domain.resolution.iter().product();
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let start_time = std::time::Instant::now();
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let mut train_loss_history = Vec::new();
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let mut val_loss_history = Vec::new();
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let mut best_val_loss = f64::MAX;
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let mut best_epoch = 0;
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// Generate synthetic training data
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let train_inputs: Vec<Vec<f64>> = (0..config.num_train_samples)
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.map(|i| {
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self.rng_state = config.seed.unwrap_or(42) + i as u64;
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(0..grid_size)
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.map(|j| {
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let x =
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(j % pde.domain.resolution[0]) as f64 / pde.domain.resolution[0] as f64;
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let y = if pde.domain.dimensions > 1 {
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(j / pde.domain.resolution[0]) as f64
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/ pde.domain.resolution.get(1).copied().unwrap_or(1) as f64
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} else {
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0.0
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};
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(std::f64::consts::PI * x).sin() * (std::f64::consts::PI * y).sin()
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+ self.random_normal() * 0.1
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})
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.collect()
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})
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.collect();
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let train_targets: Vec<Vec<f64>> = train_inputs
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.iter()
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.map(|input| {
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input
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.iter()
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.map(|&v| v * 0.5 + self.random_normal() * 0.01)
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.collect()
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})
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.collect();
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// Validation data
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let val_inputs: Vec<Vec<f64>> = (0..config.num_val_samples)
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.map(|i| {
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self.rng_state = config.seed.unwrap_or(42) + 10000 + i as u64;
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(0..grid_size)
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.map(|j| {
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let x =
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(j % pde.domain.resolution[0]) as f64 / pde.domain.resolution[0] as f64;
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(std::f64::consts::PI * x).sin() + self.random_normal() * 0.1
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})
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.collect()
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})
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.collect();
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let val_targets: Vec<Vec<f64>> = val_inputs
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.iter()
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.map(|input| input.iter().map(|&v| v * 0.5).collect())
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.collect();
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// Training loop
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let num_batches = config.num_train_samples.div_ceil(config.batch_size);
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for epoch in 0..config.epochs {
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let mut epoch_loss = 0.0;
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for batch in 0..num_batches {
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let batch_start = batch * config.batch_size;
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let batch_end = (batch_start + config.batch_size).min(config.num_train_samples);
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let batch_inputs: Vec<_> = train_inputs[batch_start..batch_end].to_vec();
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let batch_targets: Vec<_> = train_targets[batch_start..batch_end].to_vec();
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// Forward pass
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let predictions: Vec<Vec<f64>> = batch_inputs
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.iter()
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.map(|input| self.forward(input))
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.collect();
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// Compute loss
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let batch_loss = self.compute_loss(&predictions, &batch_targets);
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epoch_loss += batch_loss;
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// Backward pass (simplified)
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let lr =
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config.learning_rate * (1.0 - epoch as f64 / config.epochs as f64).max(0.1); // Learning rate decay
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self.gradient_step(lr);
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// Progress callback
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if let Some(ref callback) = progress_callback {
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callback(TrainingProgress {
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epoch: epoch + 1,
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total_epochs: config.epochs,
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batch: batch + 1,
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total_batches: num_batches,
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train_loss: batch_loss,
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val_loss: None,
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physics_loss: None,
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relative_error: None,
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learning_rate: lr,
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elapsed_seconds: start_time.elapsed().as_secs_f64(),
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});
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}
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}
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let avg_train_loss = epoch_loss / num_batches as f64;
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train_loss_history.push(avg_train_loss);
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// Validation
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let val_predictions: Vec<Vec<f64>> =
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val_inputs.iter().map(|input| self.forward(input)).collect();
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let val_loss = self.compute_loss(&val_predictions, &val_targets);
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val_loss_history.push(val_loss);
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if val_loss < best_val_loss {
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best_val_loss = val_loss;
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best_epoch = epoch + 1;
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}
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}
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self.is_trained = true;
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// Generate test data and evaluate
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let test_inputs: Vec<Vec<f64>> = (0..config.num_test_samples)
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.map(|i| {
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self.rng_state = config.seed.unwrap_or(42) + 20000 + i as u64;
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(0..grid_size)
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.map(|j| {
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let x =
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(j % pde.domain.resolution[0]) as f64 / pde.domain.resolution[0] as f64;
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(std::f64::consts::PI * x).sin() + self.random_normal() * 0.1
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})
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.collect()
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})
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.collect();
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let test_targets: Vec<Vec<f64>> = test_inputs
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.iter()
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.map(|input| input.iter().map(|&v| v * 0.5).collect())
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.collect();
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let test_metrics = self.evaluate(&test_inputs, &test_targets);
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Ok(TrainingResult {
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final_train_loss: *train_loss_history.last().unwrap_or(&0.0),
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final_val_loss: *val_loss_history.last().unwrap_or(&0.0),
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best_epoch,
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train_loss_history,
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val_loss_history,
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test_metrics,
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total_time_seconds: start_time.elapsed().as_secs_f64(),
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num_parameters: self.weights.len(),
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})
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}
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fn predict(&self, input: &[f64], query_points: &[Vec<f64>]) -> Result<Vec<f64>, NeuralOpError> {
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if !self.is_trained {
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return Err(NeuralOpError::PredictionFailed(
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"Model not trained".to_string(),
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));
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}
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let full_output = self.forward(input);
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// Interpolate at query points
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let output: Vec<f64> = query_points
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.iter()
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.map(|point| {
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// Simple nearest-neighbor interpolation
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let idx = if point.is_empty() {
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0
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} else {
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let x = point[0].clamp(0.0, 1.0);
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(x * (full_output.len() - 1) as f64).round() as usize
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};
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full_output.get(idx).copied().unwrap_or(0.0)
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})
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.collect();
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Ok(output)
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}
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fn evaluate(&self, test_inputs: &[Vec<f64>], test_outputs: &[Vec<f64>]) -> EvaluationMetrics {
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let start = std::time::Instant::now();
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let predictions: Vec<Vec<f64>> = test_inputs
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.iter()
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.map(|input| self.forward(input))
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.collect();
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let inference_time = start.elapsed().as_secs_f64() * 1000.0 / test_inputs.len() as f64;
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// Calculate metrics
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let mut total_mse = 0.0;
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let mut total_relative_l2 = 0.0;
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let mut max_error: f64 = 0.0;
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for (pred, target) in predictions.iter().zip(test_outputs.iter()) {
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let mse: f64 = pred
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.iter()
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.zip(target.iter())
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.map(|(p, t)| (p - t).powi(2))
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.sum::<f64>()
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/ pred.len() as f64;
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let target_norm: f64 = target.iter().map(|t| t.powi(2)).sum::<f64>().sqrt();
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let error_norm: f64 = pred
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.iter()
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.zip(target.iter())
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.map(|(p, t)| (p - t).powi(2))
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.sum::<f64>()
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.sqrt();
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let relative_l2 = if target_norm > 1e-10 {
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error_norm / target_norm
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} else {
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error_norm
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};
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let local_max: f64 = pred
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.iter()
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.zip(target.iter())
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.map(|(p, t)| (p - t).abs())
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.fold(0.0, f64::max);
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total_mse += mse;
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total_relative_l2 += relative_l2;
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max_error = max_error.max(local_max);
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}
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let num_samples = test_inputs.len();
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EvaluationMetrics {
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mse: total_mse / num_samples as f64,
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relative_l2: total_relative_l2 / num_samples as f64,
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max_error,
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physics_residual: None,
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num_samples,
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avg_inference_time_ms: inference_time,
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}
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}
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fn num_parameters(&self) -> usize {
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self.weights.len()
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}
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fn operator_type(&self) -> OperatorType {
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OperatorType::FNO
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}
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}
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#[cfg(test)]
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mod tests {
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use super::*;
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use neuralop_studio_shared::{
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sample_fno_config, sample_poisson_problem, sample_training_config,
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};
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#[test]
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fn test_fno_creation() {
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let config = sample_fno_config();
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let fno = FourierNeuralOperator::new(config);
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assert!(!fno.is_trained);
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assert!(!fno.weights.is_empty());
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}
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#[test]
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fn test_fno_forward() {
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let config = sample_fno_config();
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let fno = FourierNeuralOperator::new(config);
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let input = vec![1.0; 64];
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let output = fno.forward(&input);
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assert_eq!(output.len(), 64);
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}
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#[test]
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fn test_fno_training() {
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let config = sample_fno_config();
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let mut fno = FourierNeuralOperator::new(config);
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let mut training_config = sample_training_config();
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training_config.epochs = 3;
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training_config.num_train_samples = 20;
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training_config.num_val_samples = 5;
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training_config.num_test_samples = 5;
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let pde = sample_poisson_problem();
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let result = fno.train(&pde, &training_config, None);
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assert!(result.is_ok());
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assert!(fno.is_trained);
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}
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#[test]
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fn test_fno_predict_after_training() {
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let config = sample_fno_config();
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let mut fno = FourierNeuralOperator::new(config);
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let mut training_config = sample_training_config();
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training_config.epochs = 2;
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training_config.num_train_samples = 10;
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training_config.num_val_samples = 5;
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training_config.num_test_samples = 5;
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let pde = sample_poisson_problem();
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fno.train(&pde, &training_config, None).unwrap();
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let input = vec![1.0; 64];
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let query_points = vec![vec![0.5, 0.5], vec![0.25, 0.75]];
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let result = fno.predict(&input, &query_points);
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assert!(result.is_ok());
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assert_eq!(result.unwrap().len(), 2);
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}
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#[test]
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fn test_fno_predict_without_training() {
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let config = sample_fno_config();
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let fno = FourierNeuralOperator::new(config);
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let input = vec![1.0; 64];
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let query_points = vec![vec![0.5, 0.5]];
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let result = fno.predict(&input, &query_points);
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assert!(result.is_err());
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}
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#[test]
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fn test_fno_num_parameters() {
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let config = sample_fno_config();
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let fno = FourierNeuralOperator::new(config);
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assert!(fno.num_parameters() > 0);
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}
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}
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Reference in New Issue
Block a user