compute_backward<typename descriptor_type, typename data_type>¶
Computes the backward FFT. This routine belongs to the oneapi::mkl::dft
namespace.
Description¶
The compute_backward<typename descriptor_type, typename data_type>
function accepts a descriptor object followed by one or more data parameters. Given a successfully configured and committed descriptor, this function computes the backward FFT, that is, the transform with the plus sign in the exponent, \(\delta = +1\). This function throws an std::runtime_exception
in the case that it fails.
The FFT descriptor must be properly configured prior to the function call. Function calls needed to configure an FFT descriptor for a particular call to an FFT computation function are summarized in Configuring and Computing an FFT in C/C++.
The number of data parameters to be provided depends exclusively on the descriptor’s PLACEMENT configuration parameter. In-place (default) operations require only one data parameter while out-of-place operations take two distinct data parameters. The function’s behavior is undefined otherwise.
API¶
Syntax¶
Using SYCL buffers
namespace oneapi::mkl::dft{
void compute_backward<descriptor_type,
data_type>(descriptor_type &desc, sycl::buffer<data_type,
1> &inout);
void compute_backward<descriptor_type, input_type,
output_type>(descriptor_type &desc,
sycl::buffer<input_type, 1> &in,
sycl::buffer<output_type, 1> &out);
}
Using USM pointers
namespace oneapi::mkl::dft{
sycl::event compute_backward<descriptor_type,
data_type>(descriptor_type &desc, data_type* inout, const
std::vector<sycl::event> &dependencies = {});
sycl::event compute_backward<descriptor_type, input_type,
output_type>(descriptor_type &desc, input_type* in,
output_type* out, const
std::vector<sycl::event> &dependencies = {});
}
Include Files¶
oneapi/mkl/dfti.hpp
Input Parameters¶
Name |
Supported types |
Description |
---|---|---|
inout |
|
Input/output data |
in |
|
Input data |
The parameter name inout (resp. in) corresponds to using a descriptor configured to operate INPLACE (resp. NOT_INPLACE). See descriptor’s PLACEMENT.
Whether using i. SYCL buffers or ii. device-accessible USM pointers, the length of the containing array must be no less than specified at construction of the descriptor.
Output Parameters¶
Name |
Supported types |
Description |
---|---|---|
inout |
|
Input/output data |
out |
|
Output data |
The parameter name inout (resp. out) corresponds to using a descriptor configured to operate INPLACE (resp. NOT_INPLACE). See descriptor’s PLACEMENT.
Whether using i. SYCL buffers or ii. device-accessible USM pointers, the length of the containing array must be no less than specified at construction of the descriptor.
In case of out-of-place operations, the same type is to be used for the parameters in and out.