Math Vector Library
Programming Reference Manual Fortran
Version 1.1 DD-00002-111

5.2 vrsqrt - Vector reciprocal square root   ⎷--
1/ x

subroutine vrsqrt (n, y, incy, x, incx); 
subroutine vrsqrtf(n, y, incy, x, incx); 
 
subroutine vrsqrt_64 (n, y, incy, x, incx); 
subroutine vrsqrtf_64(n, y, incy, x, incx);

Given an input vector x and a result vector y, this function computes:

   -1-
y= ⎷x-
5.2.1 Parameters

N - INTEGER

ENTRY: Number of elements of x and y.
CONSTRAINT: n ≥1.

Y - ARRAY OF REAL

EXIT: Result vector y.
CONSTRAINT: Must contain n× incy elements.
CONSTRAINT: Must not overlap with array x.

INCY - INTEGER

ENTRY: Stride for the vector y.
CONSTRAINT: incy̸= 0.
BEHAVIOR: A negative stride will traverse the array in reverse.

X - ARRAY OF REAL

ENTRY: Input vector x.
CONSTRAINT: Must contain n× incx elements.
CONSTRAINT: Must not overlap with array y.

INCX - INTEGER

ENTRY: Stride for the vector x.
CONSTRAINT: incx̸= 0.
BEHAVIOR: A negative stride will traverse the array in reverse.