Update 06_multicat.ipynb (#349)

Fix binary_cross_entropy

06_multicat.ipynb

@@ -976,7 +976,7 @@
    "source": [
     "def binary_cross_entropy(inputs, targets):\n",
     "    inputs = inputs.sigmoid()\n",
-    "    return -torch.where(targets==1, inputs, 1-inputs).log().mean()"
+    "    return -torch.where(targets==1, 1-inputs, inputs).log().mean()"
    ]
   },
   {