atan(3F)

NAME
     atan, datan, qatan, atand, datand, qatand - FORTRAN arctangent intrinsic
     function

SYNOPSIS
     real r1, r2
     double precision dp1, dp2
     real*4 r3, r4
     real*8 dp3, dp4
     real*16 qp1, qp2, qp3, qp4

     r2 = atan(r1)

     dp2 = datan(dp1)
     dp2 = atan(dp1)

     qp2 = qatan(qp1)
     qp2 = atan(qp1)

     r4 = atand(r3)

     dp4 = datand(dp3)
     dp4 = atand(dp3)

     qp4 = qatand(qp3)
     qp4 = qatand(qp3)

DESCRIPTION
     atan returns the real arctangent of its real argument.  datan returns the
     double-precision arctangent of its double-precision argument.  qatan
     returns the real*16 arctangent of its real*16 argument.  The generic form
     atan may be used with a double-precision argument returning a double-
     precision value, or a real*16 argument returning a real*16 value.  The
     result of atan, datan, and qatan is in radians and is in the range -Pi/2
     <  result < Pi/2.

     atand returns the real*4 arctangent of its real*4 argument.  datand
     returns the real*8 arctangent of its real*8 argument.  qatand returns the
     real*16 arctangent of its real*16 argument.  The generic form atand may
     be used with a real*8 argument returning a real*8 value, or a real*16
     argument returning a real*16 value.  The result of atand, datand, and
     qatand is in degrees and is in the range -90 <  result < 90.

SEE ALSO
     trig(3M).