Gaussian elimination: Difference between revisions
Add Scala implementation
(Added Easylang) |
(Add Scala implementation) |
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Line 6,486:
}
}
}
</syntaxhighlight>
=={{header|Scala}}==
{{trans|Java}}
<syntaxhighlight lang="Scala">
object GaussianElimination {
def solve(a: Array[Array[Double]], b: Array[Array[Double]]): Double = {
if (a == null || b == null || a.length == 0 || b.length == 0) {
throw new IllegalArgumentException("Invalid dimensions")
}
val n = b.length
val p = b(0).length
if (a.length != n || a(0).length != n) {
throw new IllegalArgumentException("Invalid dimensions")
}
var det = 1.0
for (i <- 0 until n - 1) {
var k = i
for (j <- i + 1 until n) {
if (Math.abs(a(j)(i)) > Math.abs(a(k)(i))) {
k = j
}
}
if (k != i) {
det = -det
for (j <- i until n) {
val s = a(i)(j)
a(i)(j) = a(k)(j)
a(k)(j) = s
}
for (j <- 0 until p) {
val s = b(i)(j)
b(i)(j) = b(k)(j)
b(k)(j) = s
}
}
for (j <- i + 1 until n) {
val s = a(j)(i) / a(i)(i)
for (k <- i + 1 until n) {
a(j)(k) -= s * a(i)(k)
}
for (k <- 0 until p) {
b(j)(k) -= s * b(i)(k)
}
}
}
for (i <- n - 1 to 0 by -1) {
for (j <- i + 1 until n) {
val s = a(i)(j)
for (k <- 0 until p) {
b(i)(k) -= s * b(j)(k)
}
}
val s = a(i)(i)
det *= s
for (k <- 0 until p) {
b(i)(k) /= s
}
}
det
}
def main(args: Array[String]): Unit = {
val a = Array(
Array(4.0, 1.0, 0.0, 0.0, 0.0),
Array(1.0, 4.0, 1.0, 0.0, 0.0),
Array(0.0, 1.0, 4.0, 1.0, 0.0),
Array(0.0, 0.0, 1.0, 4.0, 1.0),
Array(0.0, 0.0, 0.0, 1.0, 4.0)
)
val b = Array(
Array(1.0 / 2.0),
Array(2.0 / 3.0),
Array(3.0 / 4.0),
Array(4.0 / 5.0),
Array(5.0 / 6.0)
)
val x = Array(39.0 / 400.0, 11.0 / 100.0, 31.0 / 240.0, 37.0 / 300.0, 71.0 / 400.0)
println("det: " + solve(a, b))
for (i <- 0 until 5) {
printf("%12.8f %12.4e\n", b(i)(0), b(i)(0) - x(i))
}
}
}
</syntaxhighlight>
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