v?Atan2

Developer Reference for Intel® oneAPI Math Kernel Library for Fortran

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ID 766686

Date 3/31/2023

Version

Public

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Computes four-quadrant inverse tangent of elements of two vectors.

Syntax

call vsatan2( n, a, b, y )

call vsatan2i(n, a, inca, b, incb, y, incy)

call vmsatan2( n, a, b, y, mode )

call vmsatan2i(n, a, inca, b, incb, y, incy, mode)

call vdatan2( n, a, b, y )

call vdatan2i(n, a, inca, b, incb, y, incy)

call vmdatan2( n, a, b, y, mode )

call vmdatan2i(n, a, inca, b, incb, y, incy, mode)

Include Files

Input Parameters

Name	Type	Description
n	INTEGER, INTENT(IN)	Specifies the number of elements to be calculated.
a, b	DOUBLE PRECISION for vdatan2, vmdatan2 REAL, INTENT(IN) for vsatan2, vmsatan2 DOUBLE PRECISION, INTENT(IN) for vdatan2, vmdatan2	Arrays that specify the input vectors a and b.
inca, incb, incy	INTEGER, INTENT(IN)	Specifies increments for the elements of `a`, `b` and `y`.
mode	INTEGER(KIND=8), INTENT(IN)	Overrides global VM mode setting for this function call. See vmlSetMode for possible values and their description.

Output Parameters

Name	Type	Description
y	DOUBLE PRECISION for vdatan2, vmdatan2 REAL, INTENT(OUT) for vsatan2, vmsatan2 DOUBLE PRECISION, INTENT(OUT) for vdatan2, vmdatan2	Array that specifies the output vector y.

Name

Type

Description

DOUBLE PRECISION for vdatan2, vmdatan2

REAL, INTENT(OUT) for vsatan2, vmsatan2

DOUBLE PRECISION, INTENT(OUT) for vdatan2, vmdatan2

Array that specifies the output vector y.

Description

The v?Atan2 function computes four-quadrant inverse tangent of elements of two vectors.

The elements of the output vectory are computed as the four-quadrant arctangent of a[i] / b[i].

Special values for Real Function v?Atan2(x)
Argument 1	Argument 2	Result	Exception
-∞	-∞	-3*`π`/4
-∞	X < +0	-`π`/2
-∞	-0	-`π`/2
-∞	+0	-`π`/2
-∞	X > +0	-`π`/2
-∞	+∞	-`π`/4
X < +0	-∞	-`π`
X < +0	-0	-`π`/2
X < +0	+0	-`π`/2
X < +0	+∞	-0
-0	-∞	-`π`
-0	X < +0	-`π`
-0	-0	-`π`
-0	+0	-0
-0	X > +0	-0
-0	+∞	-0
+0	-∞	+`π`
+0	X < +0	+`π`
+0	-0	+`π`
+0	+0	+0
+0	X > +0	+0
+0	+∞	+0
X > +0	-∞	+`π`
X > +0	-0	+`π`/2
X > +0	+0	+`π`/2
X > +0	+∞	+0
+∞	-∞	+3*`π`/4
+∞	X < +0	+`π`/2
+∞	-0	+`π`/2
+∞	+0	+`π`/2
+∞	X > +0	+`π`/2
+∞	+∞	+`π`/4
X > +0	QNAN	QNAN
X > +0	SNAN	QNAN	INVALID
QNAN	X > +0	QNAN
SNAN	X > +0	QNAN	INVALID
QNAN	QNAN	QNAN
QNAN	SNAN	QNAN	INVALID
SNAN	QNAN	QNAN	INVALID
SNAN	SNAN	QNAN	INVALID

Parent topic: Trigonometric Functions