From da1b986d311579f60445e599d29cdf42306815d8 Mon Sep 17 00:00:00 2001
From: shahules786 <shahules786@gmail.com>
Date: Thu, 3 Nov 2022 16:05:55 +0530
Subject: [PATCH] complex batchnorm 2d

---
 enhancer/models/complexnn/norm.py | 95 ++++++++++++++++++++++++++++++-
 1 file changed, 92 insertions(+), 3 deletions(-)

diff --git a/enhancer/models/complexnn/norm.py b/enhancer/models/complexnn/norm.py
index eec2130..5dd0104 100644
--- a/enhancer/models/complexnn/norm.py
+++ b/enhancer/models/complexnn/norm.py
@@ -2,7 +2,7 @@ import torch
 from torch import nn
 
 
-class ComplexBatchNorm(nn.Module):
+class ComplexBatchNorm2D(nn.Module):
     def __init__(
         self,
         num_features: int,
@@ -11,10 +11,18 @@ class ComplexBatchNorm(nn.Module):
         affine: bool = True,
         track_running_stats: bool = True,
     ):
+        """
+        Complex batch normalization 2D
+        https://arxiv.org/abs/1705.09792
+
+
+        """
+        super().__init__()
         self.num_features = num_features // 2
         self.affine = affine
         self.momentum = momentum
         self.track_running_stats = track_running_stats
+        self.eps = eps
 
         if self.affine:
             values = torch.Tensor(self.num_features)
@@ -53,7 +61,7 @@ class ComplexBatchNorm(nn.Module):
     def reset_parameters(self):
         if self.affine:
             self.Wrr.data.fill_(1)
-            self.Wii.data.fill(1)
+            self.Wii.data.fill_(1)
             self.Wri.data.uniform_(-0.9, 0.9)
             self.Br.data.fill_(0)
             self.Bi.data.fill_(0)
@@ -69,4 +77,85 @@ class ComplexBatchNorm(nn.Module):
             self.num_batches_tracked.zero_()
 
     def forward(self, input):
-        pass
+
+        real, imag = torch.chunk(input, 2, 1)
+        exp_avg_factor = 0.0
+
+        training = self.training and self.track_running_stats
+        if training:
+            self.num_batches_tracked += 1
+            if self.momentum is None:
+                exp_avg_factor = 1 / self.num_batches_tracked
+            else:
+                exp_avg_factor = self.momentum
+
+        redux = [i for i in reversed(range(real.dim())) if i != 1]
+        vdim = [1] * real.dim()
+        vdim[1] = real.size(1)
+
+        if training:
+            batch_mean_real, batch_mean_imag = real, imag
+            for dim in redux:
+                batch_mean_real = batch_mean_real.mean(dim, keepdim=True)
+                batch_mean_imag = batch_mean_imag.mean(dim, keepdim=True)
+            if self.track_running_stats:
+                self.Mean_real.lerp_(batch_mean_real.squeeze(), exp_avg_factor)
+                self.Mean_imag.lerp_(batch_mean_imag.squeeze(), exp_avg_factor)
+
+        else:
+            batch_mean_real = self.Mean_real.view(vdim)
+            batch_mean_imag = self.Mean_imag.view(vdim)
+
+        real -= batch_mean_real
+        imag -= batch_mean_imag
+
+        if training:
+            batch_var_rr = real * real
+            batch_var_ri = real * imag
+            batch_var_ii = imag * imag
+            for dim in redux:
+                batch_var_rr = batch_var_rr.mean(dim, keepdim=True)
+                batch_var_ri = batch_var_ri.mean(dim, keepdim=True)
+                batch_var_ii = batch_var_ii.mean(dim, keepdim=True)
+            if self.track_running_stats:
+                self.Var_rr.lerp_(batch_var_rr.squeeze(), exp_avg_factor)
+                self.Var_ri.lerp_(batch_var_ri.squeeze(), exp_avg_factor)
+                self.Var_ii.lerp_(batch_var_ii.squeeze(), exp_avg_factor)
+
+        batch_var_rr += self.eps
+        batch_var_ii += self.eps
+
+        # Covariance matrics
+        # | batch_var_rr    batch_var_ri |
+        # | batch_var_ir    batch_var_ii |  here batch_var_ir == batch_var_ri
+        # Inverse square root of cov matrix by combining below two formulas
+        # https://en.wikipedia.org/wiki/Square_root_of_a_2_by_2_matrix
+        # https://mathworld.wolfram.com/MatrixInverse.html
+
+        tau = batch_var_rr + batch_var_ii
+        s = batch_var_rr * batch_var_ii - batch_var_ri * batch_var_ri
+        t = (tau + 2 * s).sqrt()
+
+        rst = 1 / (s * t)
+        Urr = (batch_var_ii + s) * rst
+        Uri = -batch_var_ri * rst
+        Uii = (batch_var_rr + s) * rst
+
+        if self.affine:
+            Wrr, Wri, Wii = (
+                self.Wrr.view(vdim),
+                self.Wri.view(vdim),
+                self.Wii.view(vdim),
+            )
+            Zrr = (Wrr * Urr) + (Wri * Uri)
+            Zri = (Wrr * Uri) + (Wri * Uii)
+            Zir = (Wii * Uri) + (Wri * Urr)
+            Zii = (Wri * Uri) + (Wii * Uii)
+        else:
+            Zrr, Zri, Zir, Zii = Urr, Uri, Uri, Uii
+
+        yr = (Zrr * real) + (Zri * imag)
+        yi = (Zir * real) + (Zii * imag)
+
+        outputs = torch.cat([yr, yi], 1)
+        return outputs