我剛剛下載了Cula,我想用它實現的函數來解決線性方程組的系統問題。我查看了實例目錄,並且看到了下面的代碼,但是當他們想要獲得A * X = B的X解決方案時,的B X和因爲A是身份對角矩陣,因此,答案是,「B」,並在這行代碼沒有任何反應cula「culaSgesv」在哪裏答案?
status = culaSgesv(N, NRHS, A, N, IPIV, X, N);
(改變X到B並沒有幫助!)
你會請告訴我發生了什麼事?請告訴我如何從這裏得到答案「X」?
如果有人需要任何進一步的信息,請告訴我。
#ifdef CULA_PREMIUM
void culaDoubleExample()
{
#ifdef NDEBUG
int N = 4096;
#else
int N = 780;
#endif
int NRHS = 1;
int i;
culaStatus status;
culaDouble* A = NULL;
culaDouble* B = NULL;
culaDouble* X = NULL;
culaInt* IPIV = NULL;
culaDouble one = 1.0;
culaDouble thresh = 1e-6;
culaDouble diff;
printf("-------------------\n");
printf(" DGESV\n");
printf("-------------------\n");
printf("Allocating Matrices\n");
A = (culaDouble*)malloc(N*N*sizeof(culaDouble));
B = (culaDouble*)malloc(N*sizeof(culaDouble));
X = (culaDouble*)malloc(N*sizeof(culaDouble));
IPIV = (culaInt*)malloc(N*sizeof(culaInt));
if(!A || !B || !IPIV)
exit(EXIT_FAILURE);
printf("Initializing CULA\n");
status = culaInitialize();
checkStatus(status);
// Set A to the identity matrix
memset(A, 0, N*N*sizeof(culaDouble));
for(i = 0; i < N; ++i)
A[i*N+i] = one;
// Set B to a random matrix (see note at top)
for(i = 0; i < N; ++i)
B[i] = (culaDouble)rand();
memcpy(X, B, N*sizeof(culaDouble));
memset(IPIV, 0, N*sizeof(culaInt));
printf("Calling culaDgesv\n");
DWORD dw1 = GetTickCount();
status = culaDgesv(N, NRHS, A, N, IPIV, X, N);
DWORD dw2 = GetTickCount();
cout<<"Time difference is "<<(dw2-dw1)<<" milliSeconds"<<endl;
if(status == culaInsufficientComputeCapability)
{
printf("No Double precision support available, skipping example\n");
free(A);
free(B);
free(IPIV);
culaShutdown();
return;
}
checkStatus(status);
printf("Verifying Result\n");
for(i = 0; i < N; ++i)
{
diff = X[i] - B[i];
if(diff < 0.0)
diff = -diff;
if(diff > thresh)
printf("Result check failed: i=%d X[i]=%f B[i]=%f", i, X[i], B[i]);
}
printf("Shutting down CULA\n\n");
culaShutdown();
free(A);
free(B);
free(IPIV);
}