pow

Computes a to the power b for elements of two vectors.

Syntax

Buffer API:

void pow(queue &exec_queue, int64_t n, buffer<T, 1> &a, buffer<T, 1> &b, buffer<T, 1> &y, uint64_t mode = mode::not_defined, error_handler<T> errhandler = {})

USM API:

event pow(queue &exec_queue, int64_t n, T *a, T *b, T *y, vector_class<event> *depends, uint64_t mode = mode::not_defined, error_handler<T> errhandler = {})

pow supports the following precisions.

T
float
double
std::complex<float>
std::complex<double>

Description

The pow(a,b) function computes a to the power b for elements of two vectors.

The real function pow has certain limitations on the input range of a and b parameters. Specifically, if a[i] is positive, then b[i] may be arbitrary. For negative a[i], the value of b[i] must be an integer (either positive or negative).

The complex function pow has no input range limitations.

Argument 1	Argument 2	Result	Error Code
+0	neg. odd integer	+∞	status::errdom
-0	neg. odd integer	-∞	status::errdom
+0	neg. even integer	+∞	status::errdom
-0	neg. even integer	+∞	status::errdom
+0	neg. non-integer	+∞	status::errdom
-0	neg. non-integer	+∞	status::errdom
-0	pos. odd integer	+0
-0	pos. odd integer	-0
+0	pos. even integer	+0
-0	pos. even integer	+0
+0	pos. non-integer	+0
-0	pos. non-integer	+0
-1	+∞	+1
-1	-∞	+1
+1	any value	+1
+1	+0	+1
+1	-0	+1
+1	+∞	+1
+1	-∞	+1
+1	QNAN	+1
any value	+0	+1
+0	+0	+1
-0	+0	+1
+∞	+0	+1
-∞	+0	+1
QNAN	+0	+1
any value	-0	+1
+0	-0	+1
-0	-0	+1
+∞	-0	+1
-∞	-0	+1
QNAN	-0	+1
a < +0	non-integer	QNAN	status::errdom
|a| < 1	-∞	+∞
+0	-∞	+∞	status::errdom
-0	-∞	+∞	status::errdom
|a| > 1	-∞	+0
+∞	-∞	+0
-∞	-∞	+0
|a| < 1	+∞	+0
+0	+∞	+0
-0	+∞	+0
|a| > 1	+∞	+∞
+∞	+∞	+∞
-∞	+∞	+∞
-∞	neg. odd integer	-0
-∞	neg. even integer	+0
-∞	neg. non-integer	+0
-∞	pos. odd integer	-∞
-∞	pos. even integer	+∞
-∞	pos. non-integer	+∞
+∞	b < +0	+0
+∞	b > +0	+∞
Big finite value*	Big finite value*	+/-∞	status::overflow
QNAN	QNAN	QNAN
QNAN	SNAN	QNAN
SNAN	QNAN	QNAN
SNAN	SNAN	QNAN

* Overflow in a real function is supported only in the HA/LA accuracy modes. The overflow occurs when x and y are finite numbers, but the result is too large to fit the target precision. In this case, the function:

1. Returns ∞ in the result.

2. Sets the VM Error Status to status::overflow.

Overflow in a complex function occurs (supported in the HA/LA accuracy modes only) when all RE(x), RE(y), IM(x), IM(y) arguments are finite numbers, but the real or imaginary part of the computed result is so large that it does not fit the target precision. In this case, the function returns ∞ in that part of the result, and sets the VM Error Status to status::overflow (overriding any possible status::accuracy_warning status).

The complex double precision versions of this function are implemented in the EP accuracy mode only. If used in HA or LA mode, the functions set the VM Error Status to status::accuracy_warning.

Input Parameters

Buffer API:

exec_queue

The queue where the routine should be executed.

n

Specifies the number of elements to be calculated.

a

The buffer a containing 1st input vector of size n.

b

The buffer b containing 2nd input vector of size n.

mode

Overrides the global VM mode setting for this function call. See set_mode function for possible values and their description. This is an optional parameter. The default value is mode::not_defined.

errhandler

Sets local error handling mode for this function call. See the create_error_handler function for arguments and their descriptions. This is an optional parameter. The local error handler is disabled by default.

USM API:

exec_queue

The queue where the routine should be executed.

n

Specifies the number of elements to be calculated.

a

Pointer a to the 1st input vector of size n.

b

Pointer b to the 2nd input vector of size n.

depends

Vector of dependent events (to wait for input data to be ready).

mode

Overrides the global VM mode setting for this function call. See the set_mode function for possible values and their description. This is an optional parameter. The default value is mode::not_defined.

errhandler

Sets local error handling mode for this function call. See the create_error_handler function for arguments and their descriptions. This is an optional parameter. The local error handler is disabled by default.

Output Parameters

Buffer API:

y

The buffer y containing the output vector of size n.

USM API:

y

Pointer y to the output vector of size n.

return value (event)

Function end event.

Example

An example of how to use pow can be found in the oneMKL installation directory, under:

examples/sycl/vml/vpow.cpp

Parent topic: Power and Root Functions