Update README.md

README.md

@@ -33,7 +33,28 @@ which need to completed using only the `numpy` package.
 
 ### 2. Complete ica.py
 
-`ica.py` includes the following subroutine
+`ica.py` includes the following subroutines that need to be completed. The first
+subroutine `sample` should sample patches from images.  
+
+```python
+def sample(x, patch_size=16, num_patches=10):
+    ''' randomly sample patches from x 
+    
+        inputs:
+            x: numpy array of images
+            patch_size: patch dims for patch_size x patch_size images 
+                        (default 16)
+            num_patches: number of patches to sample (default 10)
+
+        outputs:
+            y: numpy array of patches
+    '''
+
+    return y
+```
+
+The second subroutine `ica` should perform gradient descent with the backtracking 
+line search to adapted the learning ratefor the ICA objective function. 
 
 ```python
 def ica(x, **args):