Change order of loops

Try to avoid branching in loops as it prevents vectorization

Signed-off-by: Christoph Niethammer <niethammer@hlrs.de>
This commit is contained in:
Christoph Niethammer 2024-03-13 13:46:44 +01:00
parent 39bee2e2e6
commit d6a0d64176

View file

@ -72,13 +72,12 @@ int main()
*/ */
for (int i = 2; i < dt; i++) for (int i = 2; i < dt; i++)
{ {
// Loop over spatial steps // Loop over spatial steps for flow
for (int k = 1; k < kmax; k++) for (int k = 1; k < kmax; k++) {
{
Q[k][i + 1] = Q[k][i] + h * (alpha * (P[k - 1][i] - P[k][i]) - beta * Q[k][i] * abs(Q[k][i])); Q[k][i + 1] = Q[k][i] + h * (alpha * (P[k - 1][i] - P[k][i]) - beta * Q[k][i] * abs(Q[k][i]));
}
// DO NOT calculate pressure for the last element such as it is given by default // Loop over steps for pressure, DO NOT calculate pressure for the last element as it is given as a boundary condition
if (k != kmax - 1) for (int k = 1; k < kmax - 1; k++) {
P[k][i + 1] = P[k][i - 2] + h * (gamma * (Q[k][i] - Q[k + 1][i])); P[k][i + 1] = P[k][i - 2] + h * (gamma * (Q[k][i] - Q[k + 1][i]));
} }
} }