VEC_$DMULT_CONSTANT_I             Domain/OS              VEC_$DMULT_CONSTANT_I


NAME
     vec_$dmult_constant_i - multiply a vector in a double-precision matrix by
     a scalar

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

     void vec_$dmult_constant_i(
          double *mult_vec,
          long int &inc1,
          long int &length,
          double &constant,
          double *result_vec,
          long int &inc2)

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

     procedure vec_$dmult_constant_i(
          in mult_vec: univ vec_$double_vector;
          in inc1: integer32;
          in length: integer32;
          in constant: double;
          out result_vec: univ vec_$double_vector;
          in inc2: integer32);

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

           parameter (nvec = 10)

           double precision mult_vec(nvec), result_vec(nvec), constant
           integer*4 length, inc1, inc2

           call vec_$dmult_constant_i(mult_vec, inc1, length, constant,
          &                           result_vec, inc2)

DESCRIPTION
     Vec_$dmult_constant_i multiplies length elements of the double-precision
     array mult_vec selected by inc1 by the scalar value constant, and sup-
     plies the result in elements of the array result_vec selected by inc2.

     Through appropriate choice of inc1 and inc2, a program can use
     vec_$dmult_constant_i to operate on a vector in a matrix.  To multiply
     Mth vector in a matrix by constant, choose inc1 equal to the number of
     vectors in the matrix, and place the Mth element of the matrix array at
     the beginning of mult_vec.  To place the result of the operation in the
     Nth vector of a matrix, choose inc2 equal to the number of vectors in the
     resultant matrix, and place the Nth element of the matrix array at the
     beginning of result_vec.

     In C, the resulting operation is

          j = 0;
          k = 0;
          for (i = 0; i < length; ++i) {
               result_vec[k] = constant * mult_vec[j];
               k += inc2;
               j += inc1;
          }

     In Pascal, the resulting operation is

          j := 1;
          k := 1;
          for i := 1 to length do
               begin
               result_vec[k] := constant * mult_vec[j];
               k := k + inc2;
               j := j + inc1;
               end

     In FORTRAN, the resulting operation is

           j = 1
           k = 1
           do 10 i = 1, length
               result(j) = constant * mult_vec(k)
               j = j + inc2
               k = k + inc1
       10  continue

     mult_vec
          The vector to multiply by constant.

     inc1 An increment for the index of the array mult_vec that selects ele-
          ments to multiply by constant.

     length
          The number of products to calculate.

     constant
          The scalar constant to multiply elements of mult_vec by.

     result_vec
          An array whose elements receive the product of constant and
          mult_vec.

     inc2 An increment for the index of the array result_vec that selects ele-
          ments to receive the product of constant and mult_vec.

NOTES
     In C and Pascal, vec_$dmult_constant_i operates on column vectors;
     whereas in FORTRAN, it operates on row vectors.

SEE ALSO
     vec_$dmult_constant, vec_$imult_constant16_i, vec_$imult_constant_i,
     vec_$mult_constant_i.