Add missing losses.md file.

docs/templates/losses.md

@@ -0,0 +1,29 @@
+
+## Usage of loss functions
+
+A loss function (or objective function, or optimization score function) is one of the two parameters required to compile a model:
+
+```python
+model.compile(loss='mean_squared_error', optimizer='sgd')
+```
+
+You can either pass the name of an existing loss function, or pass a TensorFlow/Theano symbolic function that returns a scalar for each data-point and takes the following two arguments:
+
+- __y_true__: True labels. TensorFlow/Theano tensor.
+- __y_pred__: Predictions. TensorFlow/Theano tensor of the same shape as y_true.
+
+The actual optimized objective is the mean of the output array across all datapoints.
+
+For a few examples of such functions, check out the [losses source](https://github.com/fchollet/keras/blob/master/keras/losses.py).
+
+## Available loss functions
+
+{{autogenerated}}
+
+**Note**: when using the `categorical_crossentropy` loss, your targets should be in categorical format (e.g. if you have 10 classes, the target for each sample should be a 10-dimensional vector that is all-zeros expect for a 1 at the index corresponding to the class of the sample). In order to convert *integer targets* into *categorical targets*, you can use the Keras utility `to_categorical`:
+
+```python
+from keras.utils.np_utils import to_categorical
+
+categorical_labels = to_categorical(int_labels, num_classes=None)
+```