Web-Projects/blog-static
1
0
Fork 0
Code Issues Pull Requests Releases Wiki Activity

Remove the code for the linear multistep article, too

Browse Source
This commit is contained in:
Danila Fedorin 2023-01-01 15:27:27 -08:00
parent 1961e545c0
commit 2d22f0b2f2
1 changed files with 0 additions and 61 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

61
code/linear-multistep/lmm.chpl
View File

@ -1,61 +0,0 @@
module LinearMultiStep {
record empty {}
record cons {
param weight;
type tail;
}
proc initial(type x : empty) param return 0;
proc initial(type x : cons(?w, ?t)) param return 1 + initial(t);
proc cff(param x : int, type ct : cons(?w, ?t)) param {
if x == 1 {
return w;
} else {
return cff(x-1, t);
}
}
proc runMethod(type method, step : real, count : int, start : real,
n : real ... initial(method)): real {
param coeffCount = initial(method);
// Repeat the methods as many times as requested
for i in 1..count {
// We're computing by adding h*b_j*f(...) to y_n.
// Set total to y_n.
var total = n(coeffCount - 1);
for param j in 1..coeffCount do
// For each coefficient b_j given by cff(j, method)
// increment the total by h*bj*f(...)
total += step * cff(j, method) *
f(start + step*(i-1+coeffCount-j), n(coeffCount-j));
// Shift each y_i over by one, and set y_{n+s} to the
// newly computed total.
for j in 0..< coeffCount - 1 do
n(j) = n(j+1);
n(coeffCount - 1) = total;
}
// return final y_{n+s}
return n(coeffCount - 1);
}
}
proc f(t: real, y: real) return y;
use LinearMultiStep;
type euler = cons(1.0, empty);
type adamsBashforth = cons(3.0/2.0, cons(-0.5, empty));
type someThirdMethod = cons(23.0/12.0, cons(-16.0/12.0, cons(5.0/12.0, empty)));
// prints 5.0625 (correct)
writeln(runMethod(euler, step=0.5, count=4, start=0, 1));
// For Adams-Bashforth, pick second initial point from Euler's method
// returns 6.0234 (correct)
writeln(runMethod(adamsBashforth, step=0.5, count=3, start=0, 1,
runMethod(euler, step=0.5, count=1, start=0, 1)));
writeln(runMethod(someThirdMethod, step=0.5, count=2, start=0,
1,
runMethod(euler, step=0.5, count=1, start=0, 1),
runMethod(adamsBashforth, step=0.5, count=1, start=0, 1, runMethod(euler, step=0.5, count=1, start=0, 1))));