From af6adc11f53fa251f6358463d112da478ad631f8 Mon Sep 17 00:00:00 2001
From: Vlad <katsmanva@gmail.com>
Date: Thu, 25 Oct 2018 00:20:10 +0300
Subject: [PATCH] fix BCEloss error

a wrapper proposed by yzgao to solve numerical instability
---
 1. Vanilla GAN PyTorch.ipynb | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/1. Vanilla GAN PyTorch.ipynb b/1. Vanilla GAN PyTorch.ipynb
index e1fe594..3182096 100644
--- a/1. Vanilla GAN PyTorch.ipynb	
+++ b/1. Vanilla GAN PyTorch.ipynb	
@@ -218,7 +218,14 @@
     "g_optimizer = optim.Adam(generator.parameters(), lr=0.0002)\n",
     "\n",
     "# Loss function\n",
-    "loss = nn.BCELoss()\n",
+    "class StableBCELoss(nn.modules.Module):",
+    "   def __init__(self):",
+    "         super(StableBCELoss, self).__init__()",
+    "   def forward(self, input, target):",
+    "         neg_abs = - input.abs()",
+    "         loss = input.clamp(min=0) - input * target + (1 + neg_abs.exp()).log()",
+    "         return loss.mean()",
+    "loss = StableBCELoss()\n",
     "\n",
     "# Number of steps to apply to the discriminator\n",
     "d_steps = 1  # In Goodfellow et. al 2014 this variable is assigned to 1\n",