add doc for adaptive pool. test=develop

paddle/fluid/operators/pool_op.cc

@@ -277,6 +277,14 @@ Example:
        Output(i ,j) = \\frac{sum(Input[hstart:hend, wstart:wend])}{(hend - hstart) * (wend - wstart)}
        $$
 
+  For adaptive = true:
+      $$
+      hstart = floor(i * H_{in} / H_{out})
+      hend = ceil((i + 1) * H_{in} / H_{out})
+      wstart = floor(j * W_{in} / W_{out})
+      wend = ceil((j + 1) * W_{in} / W_{out})
+      Output(i ,j) = \\frac{sum(Input[hstart:hend, wstart:wend])}{(hend - hstart) * (wend - wstart)}
+      $$
 )DOC");
 }
 
@@ -396,6 +404,37 @@ Example:
        H_{out} = \frac{(H_{in} - ksize[1] + 2 * paddings[1] + strides[1] -1)}{strides[1]} + 1 \\
        W_{out} = \frac{(W_{in} - ksize[2] + 2 * paddings[2] + strides[2] -1)}{strides[2]} + 1
   $$
+  For exclusive = true:
+  $$
+  dstart = i * strides[0] - paddings[0]
+  dend = dstart + ksize[0]
+  hstart = j * strides[1] - paddings[1]
+  hend = hstart + ksize[1]
+  wstart = k * strides[2] - paddings[2]
+  wend = wstart + ksize[2]
+  Output(i ,j, k) = \\frac{sum(Input[dstart:dend, hstart:hend, wstart:wend])}{ksize[0] * ksize[1] * ksize[2]}
+  $$
+  For exclusive = false:
+  $$
+  dstart = max(0, i * strides[0] - paddings[0])
+  dend = min(D, dstart + ksize[0])
+  hstart = max(0, j * strides[1] - paddings[1])
+  hend = min(H, hstart + ksize[1])
+  wstart = max(0, k * strides[2] - paddings[2])
+  wend = min(W, wstart + ksize[2])
+  Output(i ,j, k) = \\frac{sum(Input[dstart:dend, hstart:hend, wstart:wend])}{(dend - dstart) * (hend - hstart) * (wend - wstart)}
+  $$
+
+  For adaptive = true:
+  $$
+  dstart = floor(i * D_{in} / D_{out})
+  dend = ceil((i + 1) * D_{in} / D_{out})
+  hstart = floor(j * H_{in} / H_{out})
+  hend = ceil((j + 1) * H_{in} / H_{out})
+  wstart = floor(k * W_{in} / W_{out})
+  wend = ceil((k + 1) * W_{in} / W_{out})
+  Output(i ,j, k) = \\frac{sum(Input[dstart:dend, hstart:hend, wstart:wend])}{(dend - dstart) * (hend - hstart) * (wend - wstart)}
+  $$
 
 )DOC");
 }

paddle/fluid/operators/pool_with_index_op.cc

@@ -182,6 +182,12 @@ Example:
        H_{out} = \frac{(H_{in} - ksize[0] + 2 * paddings[0])}{strides[0]} + 1 \\
        W_{out} = \frac{(W_{in} - ksize[1] + 2 * paddings[1])}{strides[1]} + 1
        $$
+  
+  For adaptive = true:
+       $$
+       H_{out} = ksize[0]   W_{out} = ksize[1]
+       $$
+      
 
 )DOC");
   }
@@ -267,6 +273,11 @@ Example:
        H_{out} = \frac{(H_{in} - ksize[1] + 2 * paddings[1])}{strides[1]} + 1 \\
        W_{out} = \frac{(W_{in} - ksize[2] + 2 * paddings[2])}{strides[2]} + 1
        $$
+  
+  For adaptive = true:
+       $$
+       D_{out} = ksize[0]   H_{out} = ksize[1]   W_{out} = ksize[2]
+       $$
 
 )DOC");
   }