comparison Problems/private/collincomb.m @ 10:207a6ae9a76f version1.0

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+%COLLINCOMB Linear combination of matrix columns.
+%  Y = COLLINCOMB(A,COLS,X) computes a linear combination of the columns of
+%  the matrix A. The column indices are specified in the vector COLS, and
+%  the correspoinding coefficients are specified in the vector X. The
+%  vectors COLS and X must be of the same length. 
+%  
+%  The call Y = COLLINCOMB(A,COLS,X) is essentially equivalent to
+%
+%         Y = A(:,COLS)*X .
+%
+%  However, it is implemented much more efficiently.
+%
+%  Y = COLLINCOMB(A,ROWS,COLS,X) only works on the rows of A specified
+%  in ROWS, returning a vector of length equal to ROWS. This call is
+%  essentially equivalent to the command
+%
+%         Y = A(ROWS,COLS)*X .
+%
+%  See also ROWLINCOMB.
+
+
+%  Ron Rubinstein
+%  Computer Science Department
+%  Technion, Haifa 32000 Israel
+%  ronrubin@cs
+%
+%  April 2009