VEC_$IPOSTMULT16                  Domain/OS                   VEC_$IPOSTMULT16


NAME
     vec_$ipostmult16 - multiply a 16-bit integer vector by a 4x4 matrix

SYNOPSIS (C)
     #include <apollo/base.h>
     #include <apollo/vec.h>

     void vec_$ipostmult16(
          short *matrix,
          short *start_vec,
          short *result_vec)

SYNOPSIS (Pascal)
     %include '/sys/ins/base.ins.pas';
     %include '/sys/ins/vec.ins.pas';

     procedure vec_$ipostmult16(
          in matrix: univ vec_$integer16_matrix;
          in start_vec: univ vec_$integer16_vector;
          out result_vec: univ vec_$integer16_vector);

SYNOPSIS (FORTRAN)
     %include '/sys/ins/base.ins.ftn'
     %include '/sys/ins/vec.ins.ftn'

           integer*2 matrix(4, 4), start_vec(4), result_vec(4)

           call vec_$ipostmult16(matrix, start_vec, result_vec)

DESCRIPTION
     Vec_$ipostmult16 multiplies the 4-element vector start_vec by the 4x4
     matrix matrix.

     In C, vec_$ipostmult16 applies matrix as a right transform to a row vec-
     tor start_vec, and the resulting operation is

          for (j = 0; j < 4; ++j) {
               result_vec[j] = 0;
               for (i = 0; i < 4; ++i)
                    result_vec[j] += start_vec[i]
                                  * matrix[i][j];
          }

     In Pascal, vec_$ipostmult16 applies matrix as a right transform to a row
     vector start_vec, and the resulting operation is

          for j := 1 to 4 do
               begin
               result_vec[j] := 0;
               for i := 1 to 4 do
                    result_vec[j] := result_vec[j]
                                  + start_vec[i]
                                  * matrix[i,j];
               end

     In FORTRAN, vec_$ipostmult16 applies matrix as a left transform to a
     column vector start_vec, and the resulting operation is

           do 10 j = 1, 4
               result_vec(j) = 0
               do 10 i = 1, 4
                    result_vec(j) = result_vec(j)
          &                       + start_vec(i)
          &                       * matrix(j,i)
       10  continue

     matrix
          The matrix to multiply by start_vec.

     start_vec
          The vector to multiply by matrix.

     result_vec
          The product of start_vec and matrix.

NOTES
     Vec_$ipremult16 transforms 16-bit integer vectors from the other side.

SEE ALSO
     vec_$dpostmult, vec_$ipostmult, vec_$postmult.