add common functions

common/slice.m

@@ -0,0 +1,20 @@
+function B = slice(A, dim, index)
+% slice(A,2,index) = A(:,index,:)
+sz = size(A);
+sz(dim) = numel(index);
+IDX = cell(1,ndims(A));
+for i = 1:ndims(A)
+    if i == dim
+        idx = index;
+    else
+        idx = 1:sz(i);
+    end
+    shape = ones(1,ndims(A));
+    shape(i) = sz(i);
+    idx = reshape(idx,shape);
+    shape = sz;
+    shape(i) = 1;
+    idx = repmat(idx,shape);
+    IDX{i} = idx(:);
+end
+B = reshape(A(sub2ind(size(A),IDX{:})),sz);

common/sub.m

@@ -0,0 +1,16 @@
+function B = sub(A, varargin)
+% submat(A,i,j,k) = A(i;j;k)
+assert(ndims(A)==numel(varargin));
+sz = cellfun(@numel,varargin);
+IDX = cell(1,ndims(A));
+for i = 1:ndims(A)
+    idx = varargin{i};
+    shape = ones(1,ndims(A));
+    shape(i) = sz(i);
+    idx = reshape(idx,shape);
+    shape = sz;
+    shape(i) = 1;
+    idx = repmat(idx,shape);
+    IDX{i} = idx(:);
+end
+B = reshape(A(sub2ind(size(A),IDX{:})),sz);