LU decomposition: Difference between revisions
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(Updated D entry) |
(Updated D entry) |
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/// Creates the pivoting matrix for m. |
/// Creates the pivoting matrix for m. |
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T[][] pivotize(T)(immutable T[][] m) |
T[][] pivotize(T)(immutable T[][] m) pure nothrow |
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in { |
in { |
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assert(m.isSquare); |
assert(m.isSquare); |
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immutable n = m.length; |
immutable n = m.length; |
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auto id = iota(n) |
auto id = iota(n) |
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.map!(j=> n.iota.map!(i => cast(T)(i == j)).array) |
.map!((in j) => n.iota.map!(i => cast(T)(i == j)).array) |
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.array; |
.array; |
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/// Decomposes a square matrix A by PA=LU and returns L, U and P. |
/// Decomposes a square matrix A by PA=LU and returns L, U and P. |
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Tuple!(T[][],"L", T[][],"U", const T[][],"P") |
Tuple!(T[][],"L", T[][],"U", const T[][],"P") |
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lu(T)(immutable T[][] A) |
lu(T)(immutable T[][] A) pure nothrow |
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in { |
in { |
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assert(A.isSquare); |
assert(A.isSquare); |
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} |
} |
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immutable P = A.pivotize!T; |
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immutable A2 = matrixMul!T(P, A); |
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foreach (immutable j; 0 .. n) { |
foreach (immutable j; 0 .. n) { |
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auto f = "[%([%(%.1f, %)],\n %)]]\n\n".replicate(3); |
auto f = "[%([%(%.1f, %)],\n %)]]\n\n".replicate(3); |
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foreach (m; [a, b]) |
foreach (immutable m; [a, b]) |
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writefln(f, lu(m).tupleof); |
writefln(f, lu(m).tupleof); |
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}</lang> |
}</lang> |
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