HP MLIB User's Guide Vol. 2 7th Ed.

Chapter 12 VMATH 845
The arctangent of the elements of a vector vsatan, vdatan
Name vsatan, vdatan
The arctangent of the elements of a vector
Purpose vsatan and vdatan calculate the arctangent function of vector elements:
y(i) = atan(a(i)), for 1 <= i <= n
Usage The Fortran include file math.fi declares interfaces for these subroutines,
suitable for both VMATH and VMATH8. The interfaces are compatible with
Intel’s MKL VML (Vector Math Library).
SUBROUTINE vsatan(n, a, y)
INTEGER, INTENT(IN) :: n
REAL (KIND=4), DIMENSION(n), INTENT(IN) :: a
REAL (KIND=4), DIMENSION(n), INTENT(OUT):: y
SUBROUTINE vdatan(n, a, y)
INTEGER, INTENT(IN) :: n
REAL (KIND=8), DIMENSION(n), INTENT(IN) :: a
REAL (KIND=8), DIMENSION(n), INTENT(OUT):: y
Input n Number of elements to be calculated.
a Array of length at least n, specifying the input vector.
Output y Array of length at least n specifying the output vector.