VEC_$ISUB_MULT_CONSTANT16_I       Domain/OS        VEC_$ISUB_MULT_CONSTANT16_I


NAME
     vec_$isub_mult_constant16_i - subtract two 16-bit integer vectors, multi-
     ply by a scalar

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

     void vec_$isub_mult_constant16_i(
          short int *start_vec,
          long int &start_inc,
          short int *sub_vec,
          long int &sub_inc,
          long int &length,
          short int &constant,
          short int *result_vec,
          long int &result_inc)

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

     procedure vec_$isub_mult_constant16_i(
          in start_vec: univ vec_$integer16_vector;
          in start_inc: integer32;
          in sub_vec: univ vec_$integer16_vector;
          in sub_inc: integer32;
          in length: integer32;
          in constant: integer16;
          out result_vec: univ vec_$integer16_vector;
          in result_inc: integer32);

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

           parameter (nvec = 10)

           integer*2 start_vec(nvec), sub_vec(nvec), result_vec(nvec), constant
           integer*4 length
           integer*4 start_inc, sub_inc, result_inc

           call vec_$isub_mult_constant16_i(start_vec, start_inc, sub_vec, sub_inc,
          & length, constant, result_vec, result_inc)

DESCRIPTION
     Vec_$isub_mult_constant16_i subtracts the vector sub_vec from the vector
     start_vec, multiplies the result by the scalar constant, and stores the
     final result in result_vec.  It differs from vec_$sub_mult_constant in
     that the vectors being handled contain 16-bit integers.

     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:
     Execute the following equations length times:
     result_vec(L) = (start_vec(J) - sub_vec(K)) x constant
     J = J + start_inc
     K = K + sub_inc
     L = L + result_inc

     start_vec
          The vector to be subtracted from.

     start_inc
          The stride for start_vec.

     sub_vec
          The vector to be subtracted.

     sub_inc
          The stride for sub_vec.

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

     constant
          The scalar constant by which the result of the subtraction is multi-
          plied.

     result_vec
          The vector created by subtracting sub_vec from  start_vec and multi-
          plying the resulting vector by constant.

     result_inc
          The stride for result_vec.

NOTES
     When vec_$isub_mult_constant16_i is used to operate on matrixes in C and
     Pascal, start_vec, sub_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.

     Vec_$isub_mult_constant16_i, like all 16-bit integer routines, performs
     poorly when compared to the 32-bit integer routines.  Its use should be
     avoided wherever possible, especially on high-performance workstations.

SEE ALSO
     vec_$sub_mult_constant, vec_$add_mult_constant, vec_$sub_mult_constant_i,
     vec_$dsub_mult_constant, vec_$dsub_mult_constant_i,
     vec_$isub_mult_constant, vec_$isub_mult_constant_i,
     vec_$isub_mult_constant16.