Euler method: Difference between revisions

=={{header|Rust}}==

{{trans|Kotlin}}

<lang Rust>fn header() {

print!(" Time: ");

for t in (0..100).step_by(10) {

print!(" {:7}", t);

}

println!();

}

fn analytic() {

print!("Analytic: ");

for t in (0..=100).step_by(10) {

print!(" {:7.3}", 20.0 + 80.0 * (-0.07 * f64::from(t)).exp());

}

println!();

}

fn euler<F: Fn(f64) -> f64>(f: F, mut y: f64, step: usize, end: usize) {

print!(" Step {:2}: ", step);

for t in (0..=end).step_by(step) {

if t % 10 == 0 {

print!(" {:7.3}", y);

}

y += step as f64 * f(y);

}

println!();

}

fn main() {

header();

analytic();

for &i in &[2, 5, 10] {

euler(|temp| -0.07 * (temp - 20.0), 100.0, i, 100);

}

}</lang>

{{out}}

<pre> Time: 0 10 20 30 40 50 60 70 80 90

Analytic: 100.000 59.727 39.728 29.797 24.865 22.416 21.200 20.596 20.296 20.147 20.073

Step 2: 100.000 57.634 37.704 28.328 23.918 21.843 20.867 20.408 20.192 20.090 20.042

Step 5: 100.000 53.800 34.280 26.034 22.549 21.077 20.455 20.192 20.081 20.034 20.014

Step 10: 100.000 44.000 27.200 22.160 20.648 20.194 20.058 20.017 20.005 20.002 20.000</pre>