vrecip 

Vector reciprocal

FORMAT

  VRECIP (x, incx, y, incy, n)

Arguments

  x                   real*8
                      On entry, a one-dimensional array X of length at least
                      (1+(n-1)*incx), containing the elements of the vector
                      x.
                      On exit, x is unchanged.

  incx                integer*4
                      On entry, the increment for the array X. As incx > 0,
                      vector x is stored forward in the array, so that x(i)
                      is stored in location X(1+(i-1)*incx).
                      On exit, incx is unchanged.

  y                   real*8
                      On entry, a one-dimensional array Y of length at least
                      (1+(n-1)*incy).
                      On exit, if n <= 0, y is unchanged.  If n > 0, y is
                      overwritten; y(i) is replaced by 1/(x(i)).

  incy                integer*4
                      On entry, the increment for the array Y. As incy > 0,
                      vector y is stored forward in the array, so that y(i)
                      is stored in location Y(1+(i-1)*incy).
                      On exit, incy is unchanged.

  n                   integer*4
                      On entry, the number of elements to process.
                      On exit, n is unchanged.

Description

  The VRECIP function computes the reciprocal of n elements of a vector as
  follows:

       y(i) = 1/(x(i))

  where x and y are vectors.

Example

  INTEGER*4 N, INCX, INCY
  REAL*8 X(20), Y(20)
  INCX = 1
  INCY = 1
  N = 20
  CALL VRECIP(X,INCX,Y,INCY, N)

  This FORTRAN code shows how the reciprocal of all elements of the real
  vector x is obtained and set equal to the corresponding elements of the
  vector y.