Developer Reference for Intel® oneAPI Math Kernel Library for Fortran

ID 766686
Date 7/13/2023
Public

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v?Atan2

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

  • mkl_vml.f90

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.

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