linearfrac

Performs linear fraction transformation of vectors a and b with scalar parameters.

Syntax

Buffer API:

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

USM API:

event linearfrac(queue &exec_queue, int64_t n, T *a, T *b, T scalea, T shifta, T scaleb, T shiftb, T *y, vector_class<event> const &depends = {}, uint64_t mode = mode::not_defined, error_handler<T> errhandler = {})

linearfrac supports the following precisions and devices:

T

Devices supported

float

Host, CPU, and GPU

double

Host, CPU, and GPU

Description

The linearfrac(a,b,scalea,shifta,scaleb,shiftb) function performs a linear fraction transformation of vector a by vector b with scalar parameters: scaling multipliers scalea, scaleb and shifting addends shifta, shiftb:

y[i]=(scalea·a[i]+shifta)/(scaleb·b[i]+shiftb), i=1,2 … n

The linearfrac function is implemented in the EP accuracy mode only, therefore no special values are defined for this function. If used in HA or LA mode, linearfrac sets the VM Error Status to status::accuracy_warning. Correctness is guaranteed within the threshold limitationsdefined for each input parameter (see the table below); otherwise, the behavior is unspecified.

Threshold Limitations on Input Parameters

2EMIN/2≤ |scalea| 2(EMAX-2)/2

2EMIN/2≤ |scaleb| 2(EMAX-2)/2

|shifta| 2EMAX-2

|shiftb| 2EMAX-2

2EMIN/2≤a[i] 2(EMAX-2)/2

2EMIN/2≤b[i] 2(EMAX-2)/2

a[i] - (shifta/scalea)*(1-δ1), |δ1| 21-(p-1)/2

b[i] - (shiftb/scaleb)*(1-δ2), |δ2| 21-(p-1)/2

EMINand EMAX are the minimum and maximum exponents and p is the number of significant bits (precision) for the corresponding data type according to the ANSI/IEEE Standard 754-2008 ([IEEE754]):

  • for single precisionEMIN = -126, EMAX = 127, p = 24

  • for double precisionEMIN = -1022, EMAX = 1023, p = 53

The thresholds become less strict for common cases with scalea=0 and/or scaleb=0:

  • ifscalea=0, there are no limitations for the values of a[i] and shifta.

  • ifscaleb=0, there are no limitations for the values of b[i] and shiftb.

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.

scalea

Constant value for scaling multipliers of vector a

shifta

Constant value for shifting addend of vector a

scaleb

Constant value for scaling multipliers of vector b

shiftb

Constant value for shifting addend of vector b

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

The pointer a to thie 1st input vector of size n.

b

The pointer b to the 2nd input vector of size n.

scalea

Constant value for scaling multipliers of vector a

shifta

Constant value for shifting addend of vector a

scaleb

Constant value for scaling multipliers of vector b

shiftb

Constant value for shifting addend of vector b

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 linearfraccan be found in the Intel® oneMKL installation directory, under:

examples/sycl/vml/vllinearfrac.cpp