sub

Performs element by element subtraction of vector b from vector a.

Syntax

Buffer API:

void sub(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 sub( 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 - {} )

sub supports the following precisions.

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

Description

The sub(a, b) function performs element by element subtraction of vector a and vector b.

Argument 1	Argument 2	Result	Error Code
+0	+0	+0
+0	-0	+0
-0	+0	+0
-0	-0	-0
+∞	+∞	QNAN
+∞	-∞	+∞
-∞	+∞	-∞
-∞	-∞	QNAN
SNAN	any value	QNAN
any value	SNAN	QNAN

Specifications for special values of the complex functions are defined according to the following formula

sub(x1+i*y1,x2+i*y2) = (x1-x2) + i*(y1-y2)

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).

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 sub can be found in the oneMKL installation directory, under:

examples/sycl/vml/vsub.cpp

Parent topic: Arithmetic Functions