diff Problems/private/rowlincomb.m @ 61:42fcbcfca132

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