Developer Reference for Intel® oneAPI Math Kernel Library for Fortran

ID 766686
Date 6/24/2024
Public

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v?Atan2pi

Computes the four-quadrant inverse tangent of the ratios of the corresponding elements of two vectors divided by π.

Syntax

call vsatan2pi (n, a, b, y)

call vsatan2pii(n, a, inca, b, incb, y, incy)

call vmsatan2pi (n, a, b, y, mode)

call vmsatan2pii(n, a, inca, b, incb, y, incy, mode)

call vdatan2pi (n, a, b, y)

call vdatan2pii(n, a, inca, b, incb, y, incy)

call vmdatan2pi (n, a, b, y, mode)

call vmdatan2pii(n, a, inca, b, incb, y, incy, mode)

Include Files

  • mkl_vml.f90

Input Parameters

Name

Type

Description

n

INTEGER

Specifies the number of elements to be calculated.

a, b

REAL for vsatan2pi

REAL for vmsatan2pi

DOUBLE PRECISION for vdatan2pi

DOUBLE PRECISION for vmdatan2pi

Pointers to the arrays containing 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)

Overrides the global VM mode setting for this function call. See vmlSetMode for possible values and their description.

Output Parameters

Name

Type

Description

y

REAL for vsatan2pi

REAL for vmsatan2pi

DOUBLE PRECISION for vdatan2pi

DOUBLE PRECISION for vmdatan2pi

Pointer to an array containing the output vector y.

Description

The v?Atan2pi function computes the four-quadrant inverse tangent of the ratios of the corresponding elements of two vectors divided by π.

For the elements of the output vector y, the function computers the four-quadrant arctangent of ai/bi, with the result divided by π.

Special values for Real Function v?Atan2pi(x, y)
Argument 1 Argument 2 Result Exception
- - -3/4  
- x < +0 -1/2  
- -0 +1/2  
- +0 -1/2  
- x > +0 -1/2  
- + -1/4  
x < +0 - -1  
x < +0 -0 -1/2  
x < +0 +0 -1/2  
x < +0 + -0  
-0 - -1  
-0 x < +0 -1  
-0 -0 -1  
-0 +0 -0  
-0 x > +0 -0  
-0 + -0  
+0 - +1  
+0 x < +0 +1  
+0 -0 +1  
+0 +0 +0  
+0 x > +0 +0  
+0 + +0  
x > +0 - +1  
x > +0 -0 +1/2  
x > +0 +0 +1/2  
x > +0 + +1/4  
+ - +3/4  
+ x < +0 +1/2  
+ -0 +1/2  
+ +0 +1/2  
+ x > +0 +1/2  
+ + +1/4  
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

See Also