simplify RK logic
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Magnus Ulimoen
parent
3ab7e532c6
commit
ceee1463dd
190
src/lib.rs
190
src/lib.rs
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@ -2,7 +2,7 @@ use ndarray::{Array2, Zip};
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use wasm_bindgen::prelude::*;
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mod operators;
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use operators::{diffx, diffx_periodic, diffy, diffy_periodic, dissx, dissy};
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use operators::diffx_periodic;
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#[cfg(feature = "wee_alloc")]
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#[global_allocator]
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@ -87,150 +87,62 @@ impl Universe {
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pub fn advance(&self, fut: &mut Universe, dt: f32, work_buffers: Option<WorkBuffers>) {
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assert_eq!(self.ex.shape(), fut.ex.shape());
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let mut y_ex = self.ex.clone();
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let mut y_hz = self.hz.clone();
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let mut buffers = work_buffers
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.unwrap_or_else(|| WorkBuffers::new(self.ex.shape()[1], self.ex.shape()[0]));
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let mut k0_ex = &mut buffers.k1_ex;
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let mut k0_hz = &mut buffers.k1_hz;
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k0_ex.fill(0.0);
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k0_hz.fill(0.0);
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// u_x
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diffx_periodic(y_ex.view(), k0_ex.view_mut());
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diffx_periodic(y_hz.view(), k0_hz.view_mut());
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let mut y = buffers.y;
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let mut k = buffers.buf;
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// y = y + 1/2*dt Au_x
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y_ex.scaled_add(1.0 / 2.0 * dt, &k0_hz);
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y_hz.scaled_add(1.0 / 2.0 * dt, &k0_ex);
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let mut k1_ex = buffers.k1_ex;
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let mut k1_hz = buffers.k1_hz;
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k1_ex.fill(0.0);
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k1_hz.fill(0.0);
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diffx_periodic(y_ex.view(), k1_ex.view_mut());
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diffx_periodic(y_hz.view(), k1_hz.view_mut());
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for i in 0..4 {
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// y = y0 + c*kn
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y.0.assign(&self.ex);
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y.1.assign(&self.hz);
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match i {
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0 => {}
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1 => {
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y.0.scaled_add(1.0 / 2.0 * dt, &k[i - 1].0);
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y.1.scaled_add(1.0 / 2.0 * dt, &k[i - 1].1);
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}
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2 => {
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y.0.scaled_add(1.0 / 2.0 * dt, &k[i - 1].0);
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y.1.scaled_add(1.0 / 2.0 * dt, &k[i - 1].1);
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}
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3 => {
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y.0.scaled_add(dt, &k[i - 1].0);
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y.1.scaled_add(dt, &k[i - 1].1);
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}
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_ => {
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unreachable!();
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}
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};
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y_ex.assign(&self.ex);
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y_hz.assign(&self.hz);
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y_ex.scaled_add(1.0 / 2.0 * dt, &k1_hz);
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y_hz.scaled_add(1.0 / 2.0 * dt, &k1_ex);
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let mut k2_ex = buffers.k2_ex;
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let mut k2_hz = buffers.k2_hz;
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k2_ex.fill(0.0);
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k2_hz.fill(0.0);
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diffx_periodic(y_ex.view(), k2_ex.view_mut());
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diffx_periodic(y_hz.view(), k2_hz.view_mut());
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k[i].0.fill(0.0);
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k[i].1.fill(0.0);
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// y = y0
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y_ex.assign(&self.ex);
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y_hz.assign(&self.hz);
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y_ex.scaled_add(1.0 / 2.0 * dt, &k2_hz);
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y_hz.scaled_add(1.0 / 2.0 * dt, &k2_ex);
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let mut k3_ex = buffers.k3_ex;
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let mut k3_hz = buffers.k3_hz;
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k3_ex.fill(0.0);
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k3_hz.fill(0.0);
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diffx_periodic(y_ex.view(), k3_ex.view_mut());
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diffx_periodic(y_hz.view(), k3_hz.view_mut());
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y_ex.assign(&self.ex);
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y_hz.assign(&self.hz);
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y_ex.scaled_add(dt, &k2_hz);
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y_hz.scaled_add(dt, &k2_ex);
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let mut k4_ex = buffers.k4_ex;
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let mut k4_hz = buffers.k4_hz;
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k4_ex.fill(0.0);
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k4_hz.fill(0.0);
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diffx_periodic(y_ex.view(), k4_ex.view_mut());
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diffx_periodic(y_hz.view(), k4_hz.view_mut());
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diffx_periodic(y.0.view(), k[i].1.view_mut());
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diffx_periodic(y.1.view(), k[i].0.view_mut());
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}
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Zip::from(&mut fut.ex)
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.and(&self.ex)
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.and(&k1_hz)
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.and(&k2_hz)
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.and(&k3_hz)
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.and(&k4_hz)
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.and(&k[0].0)
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.and(&k[1].0)
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.and(&k[2].0)
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.and(&k[3].0)
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.apply(|y1, &y0, &k1, &k2, &k3, &k4| {
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*y1 = y0 + dt / 6.0 * (k1 + 2.0 * k2 + 2.0 * k3 + k4)
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});
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Zip::from(&mut fut.hz)
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.and(&self.hz)
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.and(&k1_ex)
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.and(&k2_ex)
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.and(&k3_ex)
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.and(&k4_ex)
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.and(&k[0].1)
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.and(&k[1].1)
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.and(&k[2].1)
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.and(&k[3].1)
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.apply(|y1, &y0, &k1, &k2, &k3, &k4| {
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*y1 = y0 + dt / 6.0 * (k1 + 2.0 * k2 + 2.0 * k3 + k4)
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});
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}
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pub fn advance_upwind(&self, fut: &mut Universe, dt: f32) {
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assert_eq!(self.ex.dim(), fut.ex.dim());
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let mut ad = Array2::zeros(fut.ex.dim());
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let mut y = self.ex.clone();
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// y.assign(&self.ex)
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// ad.fill(0.0);
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let mut k0 = Array2::zeros(self.ex.dim());
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diffx(y.view(), k0.view_mut());
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diffy(y.view(), k0.view_mut());
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dissx(y.view(), ad.view_mut());
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dissy(y.view(), ad.view_mut());
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k0.scaled_add(-0.5, &ad);
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// y.assign(&self.ex);
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ad.fill(0.0);
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y.scaled_add(-1.0 / 2.0 * dt, &k0);
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let mut k1 = Array2::zeros(self.ex.dim());
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diffx(y.view(), k1.view_mut());
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diffy(y.view(), k1.view_mut());
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dissx(y.view(), ad.view_mut());
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dissy(y.view(), ad.view_mut());
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k1.scaled_add(-0.5, &ad);
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y.assign(&self.ex);
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ad.fill(0.0);
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y.scaled_add(-1.0 / 2.0 * dt, &k1);
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let mut k2 = Array2::zeros(self.ex.dim());
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diffx(y.view(), k2.view_mut());
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diffy(y.view(), k2.view_mut());
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dissx(y.view(), ad.view_mut());
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dissy(y.view(), ad.view_mut());
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k2.scaled_add(-0.5, &ad);
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y.assign(&self.ex);
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ad.fill(0.0);
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y.scaled_add(-1.0 / 2.0 * dt, &k2);
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let mut k3 = Array2::zeros(self.ex.dim());
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diffx(y.view(), k3.view_mut());
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diffy(y.view(), k3.view_mut());
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dissx(y.view(), ad.view_mut());
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dissy(y.view(), ad.view_mut());
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k3.scaled_add(-0.5, &ad);
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y.assign(&self.ex);
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ad.fill(0.0);
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y.scaled_add(-dt, &k2);
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let mut k4 = Array2::zeros(self.ex.dim());
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diffx(y.view(), k4.view_mut());
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diffy(y.view(), k4.view_mut());
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dissx(y.view(), ad.view_mut());
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dissy(y.view(), ad.view_mut());
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k4.scaled_add(-0.5, &ad);
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Zip::from(&mut fut.ex)
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.and(&self.ex)
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.and(&k1)
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.and(&k2)
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.and(&k3)
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.and(&k4)
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.apply(|y1, &y0, &k1, &k2, &k3, &k4| {
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*y1 = y0 + -dt / 6.0 * (k1 + 2.0 * k2 + 2.0 * k3 + k4)
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});
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}
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pub fn get_ptr(&mut self) -> *mut u8 {
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self.ex.as_mut_ptr() as *mut u8
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}
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@ -238,28 +150,22 @@ impl Universe {
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#[wasm_bindgen]
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pub struct WorkBuffers {
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k1_ex: Array2<f32>,
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k1_hz: Array2<f32>,
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k2_ex: Array2<f32>,
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k2_hz: Array2<f32>,
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k3_ex: Array2<f32>,
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k3_hz: Array2<f32>,
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k4_ex: Array2<f32>,
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k4_hz: Array2<f32>,
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y: (Array2<f32>, Array2<f32>),
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buf: [(Array2<f32>, Array2<f32>); 4],
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}
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#[wasm_bindgen]
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impl WorkBuffers {
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pub fn new(nx: usize, ny: usize) -> Self {
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let arr = Array2::zeros((ny, nx));
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Self {
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k1_ex: Array2::zeros((ny, nx)),
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k1_hz: Array2::zeros((ny, nx)),
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k2_ex: Array2::zeros((ny, nx)),
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k2_hz: Array2::zeros((ny, nx)),
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k3_ex: Array2::zeros((ny, nx)),
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k3_hz: Array2::zeros((ny, nx)),
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k4_ex: Array2::zeros((ny, nx)),
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k4_hz: Array2::zeros((ny, nx)),
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y: (arr.clone(), arr.clone()),
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buf: [
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(arr.clone(), arr.clone()),
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(arr.clone(), arr.clone()),
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(arr.clone(), arr.clone()),
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(arr.clone(), arr),
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],
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}
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}
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}
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