// \Delta x = b
void fastpoisson(double *b, double *x, int N)
{
int i, j;
double h, h2, *lamda, *temp, *tempb;
tempb = (double *) malloc(N*N*sizeof(double));
temp = (double *) malloc(N*sizeof(double));
lamda = (double *) malloc(N*sizeof(double));
h = 1.0/(N+1);
h2 = h*h;
for(i=0; i<N*N; i++) tempb[i] = b[i];
for(i=0; i<N; i++)
{
lamda[i] = 2 - 2*cos((i+1)*M_PI*h);
}
for (i=0; i<N; i++)
{
for (j=0; j<N; j++) temp[j] = tempb[N*i+j];
fdst(temp, N);
for (j=0; j<N; j++) tempb[N*i+j] = temp[j];
}
for (i=0; i<N; i++)
{
for (j=0; j<N; j++) temp[j] = tempb[N*j+i];
fdst(temp, N);
for (j=0; j<N; j++) tempb[N*j+i] = temp[j];
}
for(i=0; i<N; i++)
{
for(j=0; j<N; j++)
{
x[N*i+j] = -1.0*h2*tempb[N*i+j]/(lamda[i] + lamda[j]);
}
}
for (i=0; i<N; i++)
{
for (j=0; j<N; j++) temp[j] = x[N*i+j];
fdst(temp, N);
for (j=0; j<N; j++) x[N*i+j] = temp[j];
}
for (i=0; i<N; i++)
{
for (j=0; j<N; j++) temp[j] = x[N*j+i];
fdst(temp, N);
for (j=0; j<N; j++) x[N*j+i] = temp[j];
}
}
bool FileStream::copyFile(const char* srcPath, const char* dstPath)
{
FileStream fsrc(srcPath, "rb");
FileStream fdst(dstPath, "wb+");
if (fsrc && fdst)
{
setvbuf(fsrc.fp(), NULL, _IONBF, 0);
setvbuf(fdst.fp(), NULL, _IONBF, 0);
size_t nbuf = 64 * 1024;
AutoFree<char> pbuf(nbuf);
while (!fsrc.eof())
{
size_t nRead = fsrc.read(pbuf, nbuf);
size_t nWrite = fdst.write(pbuf, nRead);
if (nWrite != nRead) {
throw OutOfSpaceException(BOOST_CURRENT_FUNCTION);
}
}
return true;
}
return false;
}
