New function outerprod.

Author: GunnarFarneback

ChangeLog

@@ -1,3 +1,11 @@
+2006-09-20  Gunnar Farneb�ck  <[email protected]>
+
+	* make_tensors_fast.m: Replace tensorprod with outerprod.
+
+	* make_Abc_fast.m: Replace tensorprod with outerprod.
+
+	* outerprod.m: New file.
+
 2006-03-24  Gunnar Farneb�ck  <[email protected]>
 
 	* arrayloop.m: Added pointer to neighborhoodloop.

NEWS

@@ -1,5 +1,6 @@
 2.1
 
+- New function outerprod to compute outer products of arrays.
 - New function neighborhoodloop which works like arrayloop but
   generates neighborhoods around each point, which are passed to a
   callback function.

make_Abc_fast.m

@@ -262,7 +262,7 @@
 
     case 3
 	% Set up applicability and basis functions.
-	applicability = tensorprod(a, shiftdim(a,-1), shiftdim(a,-2));
+	applicability = outerprod(a, a, a);
 	[x,y,t] = ndgrid(-n:n);
 	b = cat(4, ones(size(x)), x, y, t, x.*x, y.*y, t.*t, x.*y, x.*t, y.*t);
 	nb = size(b,4);
@@ -390,8 +390,7 @@
 
     case 4
 	% Set up applicability and basis functions.
-	applicability = tensorprod(a, shiftdim(a,-1), shiftdim(a,-2), ...
-				   shiftdim(a,-3));
+	applicability = outerprod(a, a, a, a);
 	[x,y,z,t] = ndgrid(-n:n);
 	b = cat(5, ones(size(x)), x, y, z, t, x.*x, y.*y, z.*z, t.*t, ...
 		x.*y, x.*z, x.*t, y.*z, y.*t, z.*t);

make_tensors_fast.m

@@ -277,7 +277,7 @@
 
     case 3
 	% Set up applicability and basis functions.
-	applicability = tensorprod(a, shiftdim(a,-1), shiftdim(a,-2));
+	applicability = outerprod(a, a, a);
 	[x,y,t] = ndgrid(-n:n);
 	b = cat(4, ones(size(x)), x, y, t, x.*x, y.*y, t.*t, x.*y, x.*t, y.*t);
 	nb = size(b, 4);
@@ -426,8 +426,7 @@
 
     case 4
 	% Set up applicability and basis functions.
-	applicability = tensorprod(a, shiftdim(a, -1), shiftdim(a, -2),...
-				   shiftdim(a, -3));
+	applicability = outerprod(a, a, a, a);
 	[x,y,z,t] = ndgrid(-n:n);
 	b = cat(5, ones(size(x)), x, y, z, t, x.*x, y.*y, z.*z, t.*t,...
 		x.*y, x.*z, x.*t, y.*z, y.*t, z.*t);

outerprod.m

@@ -0,0 +1,16 @@
+function z = outerprod(x, y, varargin)
+% OUTERPROD - Multiply two or more arrays to form an outer product.
+%             Singular dimensions are ignored and automatically squeezed.
+%
+% Author: Gunnar Farnebäck
+%         Computer Vision Laboratory
+%         Linköping University, Sweden
+%         [email protected]
+
+dims = [size(x) size(y)];
+dims = dims(dims ~= 1);
+z = reshape(x(:) * y(:)', dims);
+
+if length(varargin) > 0
+    z = outerprod(z, varargin{:});
+end