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// SuiteSparse/MATLAB_Tools/SSMULT/ssmult.c
// SSMULT, Copyright (c) 2007-2011, Timothy A Davis. All Rights Reserved.
// SPDX-License-Identifier: GPL-2.0+
/* ========================================================================== */
/* == ssmult ================================================================ */
/* ========================================================================== */
/* C = A*B where A and B are sparse, or variants (A'*B, A*B', etc) using either
the saxpy method (for most matrices) or the dot product method (when C is
small compared with A and/or B).
*/
#include "ssmult.h"
/* -------------------------------------------------------------------------- */
/* ssmult_invalid */
/* -------------------------------------------------------------------------- */
void ssmult_invalid (int error)
{
if (error == ERROR_DIMENSIONS)
{
mexErrMsgTxt ("Error using ==> ssmult\n"
"Inner matrix dimensions must agree.") ;
}
else if (error == ERROR_TOO_LARGE)
{
mexErrMsgTxt ("Error using ==> ssmult\n"
"Problem too large.") ;
}
}
/* -------------------------------------------------------------------------- */
/* ssmult_use_dot */
/* -------------------------------------------------------------------------- */
/* Determine workspace required for C = A'*B using the dot product method and
the saxpy method where A is m-by-n, B is m-by-k, C is n-by-k, and return
true if the dot product method would use less workspace than the saxpy
method.
*/
static int ssmult_use_dot (const mxArray *A, const mxArray *B)
{
Int *Ap ;
Int m, n, k, anz ;
size_t dot_workspace, saxpy_workspace ;
m = mxGetM (A) ;
n = mxGetN (A) ;
k = mxGetN (B) ;
Ap = (Int *) mxGetJc (A) ;
anz = Ap [n] ;
/* ssmult_dot requires a full array C of n*k Reals */
dot_workspace = n * k * sizeof (double) ; /* (twice if A or B complex) */
if (((double) n) * ((double) k) * ((double) (sizeof (double))) !=
(double) dot_workspace)
{
/* integer overflow computing dot_workspace; use saxpy method */
return (0) ;
}
/* computing T = A' requires a workspace of size m Int's, and then the
* space for T which is (m+1) Int's for the column pointers, nnz(A) Int's
* for the row indices, and nnz(A) Reals for the values. The m Int
* workspace is freed, but reallocated by ssmult_saxpy as the Flag array.
* ssmult_saxpy requires an additional m Reals workspace.
*/
saxpy_workspace =
(2*m+1 + anz) * sizeof (Int) +
+ (anz + m) * sizeof (double) ; /* (twice if A complex) */
/* use ssmult_dot if it requires less workspace */
return (dot_workspace < saxpy_workspace) ;
}
/* -------------------------------------------------------------------------- */
/* ssmult */
/* -------------------------------------------------------------------------- */
mxArray *ssmult /* returns C = A*B or variants */
(
const mxArray *A,
const mxArray *B,
int at, /* if true: trans(A) if false: A */
int ac, /* if true: conj(A) if false: A. ignored if A real */
int bt, /* if true: trans(B) if false: B */
int bc, /* if true: conj(B) if false: B. ignored if B real */
int ct, /* if true: trans(C) if false: C */
int cc /* if true: conj(C) if false: C. ignored if C real */
)
{
mxArray *C, *T = NULL ;
if (!mxIsSparse (A) || !mxIsSparse (B))
{
mexErrMsgTxt ("A and B must be sparse") ;
}
if (at)
{
if (bt)
{
if (ct)
{
/* C = (A'*B')' A is m-by-n, B is k-by-m, C is k-by-n */
C = ssmult_saxpy (B, A, bc, ac, cc, 1) ; /* C = B*A */
}
else
{
/* C = A'*B' A is m-by-n, B is k-by-m, C is n-by-k */
T = ssmult_saxpy (B, A, bc, ac, 0, 0) ; /* T = B*A */
C = ssmult_transpose (T, cc) ; /* C = T' */
}
}
else
{
if (ct)
{
/* C = (A'*B)' A is m-by-n, B is m-by-k, C is k-by-n */
if (ssmult_use_dot (B, A))
{
C = ssmult_dot (B, A, bc, ac, cc) ; /* C = B'*A */
}
else
{
T = ssmult_transpose (B, bc) ; /* T = B' */
C = ssmult_saxpy (T, A, 0, ac, cc, 1) ; /* C = T*A */
}
}
else
{
/* C = A'*B A is m-by-n, B is m-by-k, C is n-by-k */
if (ssmult_use_dot (A, B))
{
C = ssmult_dot (A, B, ac, bc, cc) ; /* C = A'*B */
}
else
{
T = ssmult_transpose (A, ac) ; /* T = A' */
C = ssmult_saxpy (T, B, 0, bc, cc, 1) ; /* C = T*B */
}
}
}
}
else
{
if (bt)
{
if (ct)
{
/* C = (A*B')' A is m-by-n, B is k-by-n, C is k-by-m */
T = ssmult_transpose (A, ac) ; /* T = A' */
C = ssmult_saxpy (B, T, bc, 0, cc, 1) ; /* C = B*T */
}
else
{
/* C = A*B' A is m-by-n, B is k-by-n, C is m-by-k */
T = ssmult_transpose (B, bc) ; /* T = B' */
C = ssmult_saxpy (A, T, ac, 0, cc, 1) ; /* C = A*T */
}
}
else
{
if (ct)
{
/* C = (A*B)' A is m-by-n, B is n-by-k, C is k-by-m */
T = ssmult_saxpy (A, B, ac, bc, 0, 0) ; /* T = A*B */
C = ssmult_transpose (T, cc) ; /* C = T' */
}
else
{
/* C = A*B A is m-by-n, B is n-by-k, C is m-by-k */
C = ssmult_saxpy (A, B, ac, bc, cc, 1) ; /* C = A*B */
}
}
}
/* ---------------------------------------------------------------------- */
/* free workspace and return result */
/* ---------------------------------------------------------------------- */
if (T) mxDestroyArray (T) ;
return (C) ;
}
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