RosettaCodeData/Task/Cholesky-decomposition/PascalABC.NET/cholesky-decomposition.pas

52 lines
1.1 KiB
ObjectPascal

function Cholesky(a: array of real): array of real;
begin
var n := Round(Sqrt(a.Length));
Result := new real[n * n];
for var i := 0 to n - 1 do
begin
for var j := 0 to i do
begin
var s := 0.0;
for var k := 0 to j - 1 do
s += Result[i * n + k] * Result[j * n + k];
if i = j then
Result[i * n + j] := Sqrt(a[i * n + i] - s)
else Result[i * n + j] := 1 / Result[j * n + j] * (a[i * n + j] - s);
end;
end;
end;
procedure ShowMatrix(a: array of real);
begin
var n := Round(Sqrt(a.Length));
for var i := 0 to n - 1 do
begin
for var j := 0 to n - 1 do
write(a[i * n + j]:10:5);
PrintLn('');
end;
end;
begin
var m1 := new real[9];
m1 := |25.0, 15.0, -5.0,
15.0, 18.0, 0.0,
-5.0, 0.0, 11.0 |;
var c1 := Cholesky(m1);
ShowMatrix(m1);
println('=>');
ShowMatrix(c1);
PrintLn('');
var m2: array of real :=
|18.0, 22.0, 54.0, 42.0,
22.0, 70.0, 86.0, 62.0,
54.0, 86.0, 174.0, 134.0,
42.0, 62.0, 134.0, 106.0 |;
var c2 := Cholesky(m2);
Showmatrix(m2);
println('=>');
ShowMatrix(c2);
end.