ATAN2(3F)ATAN2(3F)NAME
atan2, datan2, qatan2, atan2d, datan2d, qatan2d - FORTRAN arctangent
intrinsic function
SYNOPSIS
real r1, r2, r3
double precision dp1, dp2, dp3
real*16 qp1, qp2, qp3
real*4 r4, r5, r6
real*8 dp4, dp5, dp6
real*16 qp4, qp5, qp6
r3 = atan2(r1, r2)
dp3 = datan2(dp1, dp2)
dp3 = atan2(dp1, dp2)
qp3 = qatan2(qp1, qp2)
qp3 = atan2(qp1, qp2)
r6 = atan2d(r4, r5)
dp6 = datan2d(dp4, dp5)
dp6 = atan2d(dp4, dp5)
qp6 = qatan2d(qp4, qp5)
qp6 = atan2d(qp4, qp5)
DESCRIPTION
atan2 returns the arctangent of arg1/arg2 as a real value. datan2
returns the double-precision arctangent of its double-precision
arguments. qatan2 returns the real*16 arctangent of its real*16
arguments. The generic form atan2 may be used with impunity with
double-precision or real*16 arguments. If the value of the first
argument of atan2, datan2, or qatan2 is positive, the result is positive.
If the value of the first argument is negative, the result is negative.
When the value of the first argument is positive/negative zero, the
result is positive/negative zero if the second argument is positive and
positive/negative Pi if the second argument is negative. If the value of
the second argument is zero, the absolute value of the result is Pi/2.
Both arguments must not have the value zero. The result of atan2,
datan2, and qatan2 is in radians and is in the range: -Pi <= result <=
Pi.
atan2d returns the arctangent of arg1/arg2 as a real*4 value. datan2d
returns the real*8 arctangent of its real*8 arguments. qatan2d returns
the real*16 arctangent of its real*16 arguments. The generic form atan2d
may be used with impunity with real*8 or real*16 arguments. If the value
of the first argument of atan2d, datan2d, or qatan2d is positive, the
result is positive. When the value of the first argument is zero, the
result is zero if the second argument is positive and 180.0 if the second
argument is negative. If the value of the first argument is negative,
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ATAN2(3F)ATAN2(3F)
the result is negative. If the value of the second argument is zero, the
absolute value of the result is 90.0 . Both arguments must not have the
value zero. The result of atan2d, datan2d, and qdatan2d is in degrees
and is in the range: -180 degrees <= result <= 180 degrees.
SEE ALSOtrig(3M).
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