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Resistor mesh: Difference between revisions
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ReadChar;
END ResistorMesh.</lang>
=={{header|Nim}}==
{{trans|Kotlin}}
<lang Nim>const S = 10
type
NodeKind = enum nodeFree, nodeA, nodeB
Node = object
v: float
fixed: NodeKind
Mesh[H, W: static int] = array[H, array[W, Node]]
func setBoundary(m: var Mesh) =
m[1][1].v = 1.0
m[1][1].fixed = nodeA
m[6][7].v = -1.0
m[6][7].fixed = nodeB
func calcDiff[H, W: static int](m,: Mesh[H, W]; d: var Mesh[H, W]): float =
for i in 0..<H:
for j in 0..<W:
var v = 0.0
var n = 0
if i > 0:
v += m[i - 1][j].v
inc n
if j > 0:
v += m[i][j - 1].v
inc n
if i + 1 < m.H:
v += m[i + 1][j].v
inc n
if j + 1 < m.W:
v += m[i][j + 1].v
inc n
v = m[i][j].v - v / n.toFloat
d[i][j].v = v
if m[i][j].fixed == nodeFree:
result += v * v
func iter[H, W: static int](m: var Mesh[H, W]): float =
var
d: Mesh[H, W]
cur: array[NodeKind, float]
diff = 1e10
while diff > 1e-24:
m.setBoundary()
diff = calcDiff(m, d)
for i in 0..<H:
for j in 0..<W:
m[i][j].v -= d[i][j].v
for i in 0..<H:
for j in 0..<W:
var k = 0
if i != 0: inc k
if j != 0: inc k
if i < m.H - 1: inc k
if j < m.W - 1: inc k
cur[m[i][j].fixed] += d[i][j].v * k.toFloat
result = (cur[nodeA] - cur[nodeB]) / 2
when isMainModule:
var mesh: Mesh[S, S]
let r = 2 / mesh.iter()
echo "R = ", r</lang>
{{out}}
<pre>R = 1.608991241729889</pre>
=={{header|Octave}}==
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