vec_drec1() — Apollo Domain/OS SR10.3.5

VEC_$DREC1                        Domain/OS                         VEC_$DREC1


NAME
     vec_$drec1 - calculate first-order linear recurrence of double-precision
     vector

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

     void vec_$drec1(
          double *start_vec,
          double *vec_2,
          long int &count,
          double *result_vec)

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

     procedure vec_$drec1(
          in start_vec: univ vec_$double_vector;
          in vec_2: univ vec_$double_vector;
          in count: integer32;
          var result_vec: univ vec_$double_vector);

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

           parameter (nvec = 10)

           real*8 start_vec(nvec), result_vec(nvec), vec_2(nvec)
           integer*4 count

           call vec_$drec1(start_vec, vec_2, count, result_vec)

DESCRIPTION
     Vec_$drec1 calculates a first-order linear recurrence based on start_vec
     and vec_2.  It differs from vec_$rec1 in that the vectors being handled
     are double-precision floating point.

     This routine reads the first entry in the array result_vec; it then
     writes count entries into result_vec based on the following formula:

     For each integer I such that 1 <= I <= count,
     result_vec(I+1) = start_vec(I) + (vec_2(I) x result_vec(I))

     Notice that result_vec is used both for input and output, and that it
     must be large enough to hold count + 1 entries.

     start_vec
          An input vector.

     vec_2
          An input vector.

     count
          The number of elements to be operated on.

     result_vec
          The vector containing one input value and the result of the
          recurrence calculation.

NOTES
     When vec_$drec1 is used to operate on matrixes in C and Pascal,
     start_vec, vec_2, 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 smaller subset of an input.   Because of pipelining, using
     overlapping input and output arrays may cause incorrect results.


SEE ALSO
     vec_$rec1c, vec_$rec1n, vec_$rec1r, vec_$rec1cr, vec_$rec1_i, vec_$rec1,
     vec_$drec1_i, vec_$irec1, vec_$irec1_i, vec_$irec116, vec_$irec116_i.
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