VEC_$DMULT_SUB_I                  Domain/OS                   VEC_$DMULT_SUB_I


NAME
     vec_$dmult_sub_i - multiply a scalar by a single-precision vector, sub-
     tract a vector

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

     void vec_$dmult_sub_i(
          double *mult_vec,
          long int &mult_inc,
          double *start_vec,
          long int &start_inc,
          long int &length,
          double &constant,
          double *result_vec,
          long int &result_inc)

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

     procedure vec_$dmult_sub_i(
          in mult_vec: univ vec_$double_vector;
          in mult_inc: integer32;
          in start_vec: univ vec_$double_vector;
          in start_inc: integer32;
          in length: integer32;
          in constant: double;
          out result_vec: univ vec_$double_vector;
          in result_inc: integer32);

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

           parameter (nvec = 10)

           real*8 start_vec(nvec), mult_vec(nvec), result_vec(nvec), constant
           integer*4 length
           integer*4 mult_inc, start_inc, result_inc

           call vec_$dmult_sub_i(mult_vec, mult_inc, start_vec, start_inc,
          & length, constant, result_vec, result_inc)

DESCRIPTION
     Vec_$dmult_sub_i multiplies the vector mult_vec by the scalar constant,
     subtracts the vector start_vec from the result, and stores the final
     result in result_vec.  It differs from vec_$mult_sub_i in that the vec-
     tors being handled are double-precision floating point.

     This call, like all vec_$ calls ending in _i, takes a set of extra stride
     arguments, one for every vector argument.  The stride arguments determine
     which elements in the array are actually processed.  For instance, if the
     stride for a particular array is set to 3, every third element in the
     array will be processed by the routine.  The stride arguments need not be
     identical.  If all stride arguments are set to 1, this call behaves
     exactly like the version without the _i in its name.

     The calculation performed is as follows:  Initialize the counter vari-
     ables J, K,  and L to the low indices of the arrays mult_vec, start_vec,
     and result_vec.  In Fortran, the low index will be 1;  in C, it will be
     0; in Pascal, it varies depending on the declaration.
     Execute the following equations length times:
     result_vec(L) = (constant x mult_vec(J))-start_vec(K)
     J = J + mult_inc
     K = K + start_inc
     L = L + result_inc


     Note that the multiplication done by this call is point-wise.  This call
     does not perform matrix multiplication, since the product of two vectors
     is another vector of the same magnitude.

     mult_vec
          The vector to be multiplied.

     mult_inc
          The stride for mult_vec.

     start_vec
          The vector to be subtracted.

     start_inc
          The stride for start_vec.

     length
          The number of elements to be operated on;  normally the same as the
          number of elements in the vectors.

     constant
          The scalar by which mult_vec is multiplied.

     result_vec
          The vector created by multiplying mult_vec by constant and subtract-
          ing  start_vec from the result.

     result_inc
          The stride for result_vec.

NOTES
     When vec_$dmult_sub_i is used to operate on matrixes in C and Pascal,
     mult_vec, start_vec, and result_vec are row vectors; in FORTRAN, they are
     column vectors.

     As in all the vec_$ calls, the result array must not overlap any of the
     input arrays; the result array may be identical to an input, but must not
     contain any subset of it.   Because of pipelining, using overlapping
     input and output arrays may cause incorrect results.


SEE ALSO
     vec_$add_mult, vec_$sub_mult, vec_$mult_add, vec_$mult_sub,
     vec_$mult_sub_i, vec_$dmult_sub, vec_$imult_sub, vec_$imult_sub_i,
     vec_$imult_sub16, vec_$imult_sub16_i.