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63 lines
1.5 KiB
63 lines
1.5 KiB
-- Writen by Attractive Chaos; distributed under the MIT license
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matrix = {}
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function matrix.T(a: table)
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local m: integer, n: integer, x: table = #a, @integer(#a[1]), {};
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for i = 1, n do
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local xi: number[] = table.numarray(n, 0.0)
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x[i] = xi
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for j = 1, m do xi[j] = @number (a[j][i]) end
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end
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return x;
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end
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function matrix.mul(a: table, b: table)
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assert(@integer(#a[1]) == #b);
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local m: integer, n: integer, p: integer, x: table = #a, @integer(#a[1]), @integer(#b[1]), {};
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local c: table = matrix.T(b); -- transpose for efficiency
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for i = 1, m do
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local xi: number[] = table.numarray(p, 0.0)
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x[i] = xi
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for j = 1, p do
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local sum: number, ai: number[], cj: number[] = 0.0, @number[](a[i]), @number[](c[j]);
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-- for luajit, caching c[j] or not makes no difference; lua is not so clever
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for k = 1, n do sum = sum + ai[k] * cj[k] end
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xi[j] = sum;
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end
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end
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return x;
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end
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function matgen(n: integer)
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local a: table, tmp: number = {}, 1. / n / n;
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for i = 1, n do
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local ai: number[] = table.numarray(n, 0.0)
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a[i] = ai
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for j = 1, n do
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ai[j] = tmp * (i - j) * (i + j - 2)
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end
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end
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return a;
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end
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--ravi.dumplua(matgen)
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if ravi and ravi.jit() then
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assert(ravi.compile(matrix.T))
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assert(ravi.compile(matrix.mul, {omitArrayGetRangeCheck=1}))
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assert(ravi.compile(matgen))
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end
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local n = arg[1] or 1000;
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n = math.floor(n/2) * 2;
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if jit then
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-- luajit warmup
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matrix.mul(matgen(n), matgen(n))
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end
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local t1 = os.clock()
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local a = matrix.mul(matgen(n), matgen(n))
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local t2 = os.clock()
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print("time taken ", t2-t1)
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print(a[n/2+1][n//2+1]);
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