topic Re:Trouble in multi-transforms with mkl-dft1d in Intel® oneAPI Math Kernel Library

Trouble in multi-transforms with mkl-dft1d

Nevermore — Wed, 11 May 2022 01:15:49 GMT

int _calc_fft_batch(int num_points, int batchsize, double* T, double* F) { DFTI_DESCRIPTOR_HANDLE fft_handle = NULL; MKL_LONG retval = DFTI_NO_ERROR; const int alignment = 64; retval = DftiCreateDescriptor(&fft_handle, DFTI_DOUBLE, DFTI_REAL, 1, (MKL_LONG)num_points); //CheckDftiError(retval, "DftiCreateDescriptor"); retval = DftiSetValue(fft_handle, DFTI_CONJUGATE_EVEN_STORAGE, DFTI_COMPLEX_COMPLEX); retval = DftiSetValue(fft_handle, DFTI_NUMBER_OF_TRANSFORMS, (MKL_LONG)batchsize); retval = DftiSetValue(fft_handle, DFTI_INPUT_DISTANCE, (MKL_LONG)num_points); retval = DftiSetValue(fft_handle, DFTI_OUTPUT_DISTANCE, (MKL_LONG)num_points); //retval = DftiSetValue(fft_handle, DFTI_INPUT_STRIDES, (MKL_LONG)1); //retval = DftiSetValue(fft_handle, DFTI_OUTPUT_STRIDES, (MKL_LONG)1); retval = DftiSetValue(fft_handle, DFTI_PLACEMENT, DFTI_NOT_INPLACE); //CheckDftiError(retval, "DftiSetValue"); retval = DftiCommitDescriptor(fft_handle); //CheckDftiError(retval, "DftiCommitDescriptor"); MKL_Complex16* C = (MKL_Complex16*)MKL_malloc(static_cast<size_t>(num_points * batchsize) * sizeof(MKL_Complex16), alignment); retval = DftiComputeForward(fft_handle, T, C); //CheckDftiError(retval, "DftiComputeForward"); retval = DftiFreeDescriptor(&fft_handle); //CheckDftiError(retval, "DftiFreeDescriptor"); // unpack //size_t index = 0; //for (int i = 0; i < batchsize; i++) { // for (int j = num_points / 2 + 1; j < num_points; j++) { // index = static_cast<size_t>(i * num_points); // C[index + j].real = C[index + num_points - j].real; // C[index + j].imag = (-1) * C[index + num_points - j].imag; // } //} // norm2 fft vzAbs(num_points, C, F); MKL_free(C); return retval; }

I have a double* c-array T, has shape as 1000*2048.I want to implement 1d-dft for 1000 times on T using DFTI_NUMBER_OF_TRANSFORMS instead of for loop, however only the first 2048 elements in T are computed correctly. The others are all 0.

Re:Trouble in multi-transforms with mkl-dft1d

ShanmukhS_Intel — Wed, 11 May 2022 16:19:48 GMT

Hi,

Thanks for posting on Intel Communities.

Could you please share us a working reproducer and steps(if any) so that we could try reproducing the issue at our end.

Best Regards,

Shanmukh.SS

Re: Re:Trouble in multi-transforms with mkl-dft1d

Nevermore — Thu, 12 May 2022 01:22:44 GMT

Thank u for replying. I'm appreciated it.

Code blew is my function for the single 1d c-array.

int _calc_fft(int num_points, double *t, double *f) { DFTI_DESCRIPTOR_HANDLE fft_handle = NULL; MKL_LONG retval = DFTI_NO_ERROR; const int alignment = 64; retval = DftiCreateDescriptor(&fft_handle, DFTI_DOUBLE, DFTI_REAL, 1, (MKL_LONG)num_points); //CheckDftiError(retval, "DftiCreateDescriptor"); retval = DftiSetValue(fft_handle, DFTI_PLACEMENT, DFTI_NOT_INPLACE); retval = DftiSetValue(fft_handle, DFTI_CONJUGATE_EVEN_STORAGE, DFTI_COMPLEX_COMPLEX); //CheckDftiError(retval, "DftiSetValue"); retval = DftiCommitDescriptor(fft_handle); //CheckDftiError(retval, "DftiCommitDescriptor"); MKL_Complex16* c = (MKL_Complex16*)MKL_malloc(num_points * sizeof(MKL_Complex16), alignment); retval = DftiComputeForward(fft_handle, t, c); //CheckDftiError(retval, "DftiComputeForward"); retval = DftiFreeDescriptor(&fft_handle); //CheckDftiError(retval, "DftiFreeDescriptor"); // unpack for (int i = num_points / 2 + 1; i < num_points; i++) { c[i].real = c[num_points - i].real; c[i].imag = (-1) * c[num_points - i].imag; } // norm2 fft vzAbs(num_points, c, f); MKL_free(c); return retval; }

Here is example for how I use the function in for-loop.

h = 1000; w = 800; n = 2048;

Y21 is the input 1d double* c-array (1000*800*2048) read from the file.

Here is part of Y21 (10*2048), and the input array is correct.

In this case, n=2048 length input data is handled once we call this function.

double* F1 = (double*)MKL_malloc((h * w * n) * sizeof(double), 64); t0 = std::chrono::high_resolution_clock::now(); iter = 0; for (int i = 0; i < h; i++) { for (int j = 0; j < w; j++) { _calc_fft(n, &Y21[iter * n], &F1[iter * n]); iter += 1; } } t1 = std::chrono::high_resolution_clock::now(); dbg(std::chrono::duration_cast<std::chrono::duration<double>>(t1 - t0).count() * 1000 , "ms\n");

Here is an example of how I use DFTI_NUMBER_OF_TRANSFORMS function for the same input. In this case, w*n=800*2048 length input data is handled once we call this function.

t0 = std::chrono::high_resolution_clock::now(); for (int i = 0; i < h; i++) { _calc_fft_batch(n, w, &Y21[i * (w * n)], &F2[i * (w * n)]); } t1 = std::chrono::high_resolution_clock::now(); dbg(std::chrono::duration_cast<std::chrono::duration<double>>(t1 - t0).count() * 1000 , "ms\n");

Re: Re:Trouble in multi-transforms with mkl-dft1d

Nevermore — Thu, 12 May 2022 01:39:50 GMT

Thank u for replying. Appreciate it.

Here is my function for one-time calculation.

int _calc_fft(int num_points, double *t, double *f) { DFTI_DESCRIPTOR_HANDLE fft_handle = NULL; MKL_LONG retval = DFTI_NO_ERROR; const int alignment = 64; retval = DftiCreateDescriptor(&fft_handle, DFTI_DOUBLE, DFTI_REAL, 1, (MKL_LONG)num_points); //CheckDftiError(retval, "DftiCreateDescriptor"); // 参数设置 retval = DftiSetValue(fft_handle, DFTI_PLACEMENT, DFTI_NOT_INPLACE); retval = DftiSetValue(fft_handle, DFTI_CONJUGATE_EVEN_STORAGE, DFTI_COMPLEX_COMPLEX); //CheckDftiError(retval, "DftiSetValue"); retval = DftiCommitDescriptor(fft_handle); //CheckDftiError(retval, "DftiCommitDescriptor"); MKL_Complex16* c = (MKL_Complex16*)MKL_malloc(num_points * sizeof(MKL_Complex16), alignment); retval = DftiComputeForward(fft_handle, t, c); //CheckDftiError(retval, "DftiComputeForward"); retval = DftiFreeDescriptor(&fft_handle); //CheckDftiError(retval, "DftiFreeDescriptor"); // unpack for (int i = num_points / 2 + 1; i < num_points; i++) { c[i].real = c[num_points - i].real; c[i].imag = (-1) * c[num_points - i].imag; } // norm2 fft vzAbs(num_points, c, f); MKL_free(c); return retval; }

Here is the example.

Y is 1d double*c-array with length=h*w*n, read from file, and [h, w, n] = [30, 1000, 2048].

Here is part of my input array Y (10*2048) .

double* F1 = (double*)MKL_malloc((h * w * n) * sizeof(double), 64); t0 = std::chrono::high_resolution_clock::now(); iter = 0; for (int i = 0; i < h; i++) { for (int j = 0; j < w; j++) { _calc_fft(n, &Y[iter * n], &F1[iter * n]); iter += 1; } } t1 = std::chrono::high_resolution_clock::now(); dbg(std::chrono::duration_cast<std::chrono::duration<double>>(t1 - t0).count() * 1000 , "ms\n");

Here is part of my output array F (10*2048) . U can see in for-loop it's correct.

Here is the example of using DFTI_NUMBER_OF_TRANSFORMS.

double* F2 = (double*)MKL_malloc((h * w * n) * sizeof(double), 64); t0 = std::chrono::high_resolution_clock::now(); for (int i = 0; i < h; i++) { _calc_fft_batch(n, w, &Y[i * (w * n)], &F2[i * (w * n)]); } t1 = std::chrono::high_resolution_clock::now(); dbg(std::chrono::duration_cast<std::chrono::duration<double>>(t1 - t0).count() * 1000 , "ms\n");

Here is part of my output array F (10*2048). Only the 1st 2048 output data is correct and others remain 0.

Re:Trouble in multi-transforms with mkl-dft1d

ShanmukhS_Intel — Thu, 19 May 2022 16:51:50 GMT

Hi,

Thank you for sharing the code snippets.

Could you please share us your environment details and VS project file or a working code, as with the shared snippets we are unable to compile and build the entire code.

Best Regards,

Shanmukh.SS

Re:Trouble in multi-transforms with mkl-dft1d

ShanmukhS_Intel — Thu, 26 May 2022 14:59:30 GMT

Hi,

A gentle reminder:

Could you please share us your environment details and VS project file or a working code, as with the shared snippets we are unable to compile and build the entire code.

Best Regards,

Shanmukh.SS

Re: Re:Trouble in multi-transforms with mkl-dft1d

Nevermore — Mon, 30 May 2022 01:17:53 GMT

My env:

os: WIN10

VS: 2022

MKL: 2022.0.2

CMake: 3.22

I use CMake to build the project.

Btw, I use fftw_plan_many_dft_r2c in MKL successfully, but I am still confused about why it fails when using dfti DFTI_NUMBER_OF_TRANSFORMS for multiple-arrays.

Re: Trouble in multi-transforms with mkl-dft1d

ShanmukhS_Intel — Wed, 22 Jun 2022 03:32:30 GMT

Hi,

Thanks for sharing the environment details.

We would request you to share with us a working reproducer or a Visual Studio project file so that we could look into your issue further.

In addition, Could you please check your configuration settings/storage schemes and the type of array of elements which are been computed as mentioned in the below link?

https://www.intel.com/content/www/us/en/develop/documentation/onemkl-developer-reference-fortran/top/fourier-transform-functions/fft-functions/configuration-settings/dfti-complex-real-conj-even-storage.html

Best Regards,

Shanmukh.SS

Re:Trouble in multi-transforms with mkl-dft1d

ShanmukhS_Intel — Mon, 06 Jun 2022 16:59:08 GMT

Hi,

A gentle reminder:

We would request you to share us a working reproducer or a Visual studio working project file, so that we could investigate the issue further.

Best Regards,

Shanmukh.SS

Re: Re:Trouble in multi-transforms with mkl-dft1d

sudoLife — Sun, 12 Jun 2022 09:44:01 GMT

Hi,

I am also having the OP's problem.

My descriptor is as follows:

auto status = DftiCreateDescriptor(&rangeHandle, DFTI_DOUBLE, DFTI_REAL, 1, rangePadding); status = DftiSetValue(rangeHandle, DFTI_NUMBER_OF_TRANSFORMS, rxNum); status = DftiSetValue(rangeHandle, DFTI_INPUT_DISTANCE, rangePadding); status = DftiSetValue(rangeHandle, DFTI_OUTPUT_DISTANCE, rangePadding); status = DftiSetValue(rangeHandle, DFTI_PLACEMENT, DFTI_NOT_INPLACE); status = DftiCommitDescriptor(rangeHandle);

where rangePadding = 4096, rxNum = 8.

The input is flat array of doubles, its size is rangePadding * rxNum;

The output is flat array of std::complex (I tried with Ipp64fc, makes no difference), its size is rangePadding * rxNum.

What I am experiencing is that only half of the array is filled.

What could be the problem here?

Am I missing something about the way OUTPUT_DISTANCE works?

Re: Trouble in multi-transforms with mkl-dft1d

ShanmukhS_Intel — Tue, 14 Jun 2022 05:48:40 GMT

Hi,

@Nevermore, We assume that your issue is resolved. If you need any additional information, please post a new question as this thread will no longer be monitored by Intel.

@sudoLife, We would like to request you to share the required details in a new thread and a reproducer, so that we could help you in assisting the query.

Best Regards,

Shanmukh,SS

Re: Re:Trouble in multi-transforms with mkl-dft1d

Nevermore — Mon, 20 Jun 2022 07:39:11 GMT

// unpack for (int i = num_points / 2 + 1; i < num_points; i++) { c[i].real = c[num_points - i].real; c[i].imag = (-1) * c[num_points - i].imag; }

U may need this. The rest of the conjugate parts are not calculated yet for speeding up.

Re: Re:Trouble in multi-transforms with mkl-dft1d

sudoLife — Tue, 21 Jun 2022 06:38:59 GMT

Hi,

Thanks for the information. I will test this.

For those who don't quite follow: this link will explain what's up.

UPD: I posted a solution to my (and probably this) problem in a separate thread .