GEO_mat_vec_mul3.c

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/* file: GEO_mat_vec_mul3.c */
 
#include "GEO_basic.h"
#include "GEO_util.h"
 
void GEO_mat_vec_mul3(
    double mat[3][3],
    double vec1[3],
    double vec[3]
    )
{
/*
!C*****************************************************************************
!Description:   subroutine in the utility functions of the Level-1A geolocation
               software to perform multiplication of a matrix and a vector.
 
!Input Parameters:
                double mat[3][3] - the 3x3 matrix 
                double vec1[3] - the vector (with 3 elements)
 
!Output Parameters:
                double vec[3] - output vector with 3 elements
 
!Revision History:
        $Log: GEO_mat_vec_mul3.c,v $
        Revision 1.4  1997/07/21 16:24:34  kuyper
        Baselined Version 1
 
 * Revision 1.4  1997/03/26  18:10:14  fhliang
 * Initial revision of SDST delivery of GEO_mat_vec_mul3.c.
 *
        Revision 1.3  1996/07/23 23:28:50  kuyper
        Inserted required '!'s in comments.
        Changed to return void, not int.
        Changed constants to double, to avoid conversions.
 
        Revision 1.2  1996/07/18 19:49:36  kuyper
        Included self-checking header file.
 
 
        4/5/95
        Ruiming Chen
        Finished coding.
 
        6/12/95
        Frederick S. Patt (patt@modis-xl.gsfc.nasa.gov)
        Revised prolog
 
!Team-unique Header:
                This software is developed by the MODIS Science Data Support
                Team for the National Aeronautics and Space Administration,
                Goddard Space Flight Center, under contract NAS5-32373.
 
!END*************************************************************************
*/
 
  int i = 0;  /* iteration parameter */
  int j = 0;  /* iteration parameter */
 
  /* multiplication of a matrix mat[3][3] and a vector vec1[3] */   
  for (i = 0; i < 3; ++i) {
    vec[i] = 0.0;
    for (j = 0; j < 3; ++j)
      vec[i] += mat[i][j] * vec1[j];    
  }
 
  return;
}