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shift rk4

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Magnus Ulimoen
2020-02-19 21:35:20 +01:00
parent 5d4d8370bd
commit 89e64ba33a
1 changed files with 18 additions and 12 deletions
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30
sbp/src/integrate.rs
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@@ -17,17 +17,31 @@ pub(crate) fn rk4<'a, F: 'a, SBP, RHS, WB>(
{
assert_eq!(prev.shape(), fut.shape());
for i in 0..4 {
// y = y0 + c*kn
fut.assign(prev);
for i in 0.. {
match i {
0 => {}
0 => {
fut.assign(prev);
}
1 | 2 => {
fut.assign(prev);
fut.scaled_add(1.0 / 2.0 * dt, &k[i - 1]);
}
3 => {
fut.assign(prev);
fut.scaled_add(dt, &k[i - 1]);
}
4 => {
Zip::from(&mut **fut)
.and(&**prev)
.and(&*k[0])
.and(&*k[1])
.and(&*k[2])
.and(&*k[3])
.apply(|y1, &y0, &k1, &k2, &k3, &k4| {
*y1 = y0 + dt / 6.0 * (k1 + 2.0 * k2 + 2.0 * k3 + k4)
});
return;
}
_ => {
unreachable!();
}
@@ -35,12 +49,4 @@ pub(crate) fn rk4<'a, F: 'a, SBP, RHS, WB>(
rhs(&mut k[i], &fut, grid, &mut wb);
}
Zip::from(&mut **fut)
.and(&**prev)
.and(&*k[0])
.and(&*k[1])
.and(&*k[2])
.and(&*k[3])
.apply(|y1, &y0, &k1, &k2, &k3, &k4| *y1 = y0 + dt / 6.0 * (k1 + 2.0 * k2 + 2.0 * k3 + k4));
}