ฉันใช้สูตรที่กำหนดโดย @ Max Hutchinson กับ CUBlas และ Cuda Thrust และเปรียบเทียบกับเครื่องมือคำนวณผลต่าง co แบบออนไลน์ ดูเหมือนว่าฉันจะให้ผลลัพธ์ที่ดี รหัสด้านล่างนี้ได้วางแผนไว้ที่ QDA Bayes เมทริกซ์ที่ให้มาอาจมีมากกว่าหนึ่งคลาส ดังนั้นจึงมีการคำนวณเมทริกซ์ความแปรปรวนร่วมหลายรายการ ฉันหวังว่ามันจะมีประโยชน์สำหรับใครบางคน
//! Calculates one or more than one coVarianceMatrix given data.
// There can be many classes since many covariance matrixes.
/*!
\param inMatrix This vector contains matrix data in major storage.
Forexample if inMatrix=[1 2 3 4 5 6] and trialSizes=[2] this means matrix we will work on a matrix like :
|1 4 |
|2 5 |
|3 6 | -> 2 Trials, 3 Features. Columns contains feature rows contains trials (samples)
\param trialSizes There can be many classes since many covariance matrixes. Samples from all classes will be given with inMatrix.
But we need to know how many trials(samples) we have for each class.
For example if inMatrix=[1 2 3 4 5 6 7 8 9 10 11 12] and trialSizes=[2,2]
this means matrix we will work on a matrix like :
|1 4 | |7 10 |
|2 5 | |8 11 |
|3 6 | |9 12 | --> Total number of trials(samples which is total rowCount) 2 + 2 = 4 ,
So colSize = inMatrix.size()/4 = 3(feature vector size)
--> There is two element in trialSize vec so each vector has to samples
*/
void multiQDACovianceCalculator(std::vector<float>& inMatrix, std::vector<int>& trialSizes)
{
cublasHandle_t handle; // CUBLAS context
int classCount = trialSizes.size();
int rowSize = std::accumulate(trialSizes.begin(), trialSizes.end(), 0);
int dimensionSize = inMatrix.size() / rowSize;
float alpha = 1.0f;
float beta = 0.0f; // bet =1
thrust::device_vector<float> d_cov1(dimensionSize * dimensionSize);
thrust::device_vector<float> d_cov2(dimensionSize * dimensionSize);
thrust::device_vector<float> d_covResult(dimensionSize * dimensionSize);
thrust::device_vector<float> d_wholeMatrix(inMatrix);
thrust::device_vector<float> d_meansVec(dimensionSize); // rowVec of means of trials
float *meanVecPtr = thrust::raw_pointer_cast(d_meansVec.data());
float *device2DMatrixPtr = thrust::raw_pointer_cast(d_wholeMatrix.data());
auto maxTrialNumber = *std::max_element(trialSizes.begin(), trialSizes.end());
thrust::device_vector<float> deviceVector(maxTrialNumber, 1.0f);
cublasCreate(&handle);
// Inside of for loop one covariance matrix calculated each time
for (int i = 0; i < trialSizes.size(); i++)
{
// X*transpose(X) / N
alpha = 1.0f / trialSizes[i];
cublasSgemm(handle, CUBLAS_OP_N, CUBLAS_OP_T, dimensionSize, dimensionSize, trialSizes[i], &alpha,
device2DMatrixPtr, dimensionSize, device2DMatrixPtr, dimensionSize, &beta,
thrust::raw_pointer_cast(d_cov1.data()), dimensionSize);
// Mean vector of each column
alpha = 1.0f;
cublasSgemv(handle, CUBLAS_OP_N, dimensionSize, trialSizes[i], &alpha, device2DMatrixPtr,
dimensionSize, thrust::raw_pointer_cast(deviceVector.data()), 1, &beta, meanVecPtr, 1);
// MeanVec * transpose(MeanVec) / N*N
alpha = 1.0f / (trialSizes[i] * trialSizes[i]);
cublasSgemm(handle, CUBLAS_OP_T, CUBLAS_OP_N, dimensionSize, dimensionSize, 1, &alpha,
meanVecPtr, 1, meanVecPtr, 1, &beta,
thrust::raw_pointer_cast(d_cov2.data()), dimensionSize);
alpha = 1.0f;
beta = -1.0f;
// (X*transpose(X) / N) - (MeanVec * transpose(MeanVec) / N*N)
cublasSgeam(handle, CUBLAS_OP_N, CUBLAS_OP_N, dimensionSize, dimensionSize, &alpha,
thrust::raw_pointer_cast(d_cov1.data()), dimensionSize, &beta, thrust::raw_pointer_cast(d_cov2.data()),
dimensionSize, thrust::raw_pointer_cast(d_covResult.data()), dimensionSize);
// Go to other class and calculate its covarianceMatrix
device2DMatrixPtr += trialSizes[i] * dimensionSize;
}
printVector(d_covResult);
cublasDestroy(handle);
}