mlemanczyk/even-perfect-numbers-scanner
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Align GPU prime sieve with CPU GCD heuristic

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Marek Lemańczyk committed 2025-09-20 19:48:36 +02:00
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commit 1ec71f8cfd
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+4 -1
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PerfectNumbers.Core/PrimeTester.cs
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@@ -255,13 +255,16 @@ public sealed class PrimeTester(bool useInternal = false)
return; return;
} }
// Early reject special gcd heuristic with floor(log2 n) if ((n % 10UL) == 1UL)
{
// Early reject special GCD heuristic with floor(log2 n)
ulong m = 63UL - (ulong)ILGPU.Algorithms.XMath.LeadingZeroCount(n); ulong m = 63UL - (ulong)ILGPU.Algorithms.XMath.LeadingZeroCount(n);
if (BinaryGcdGpu(n, m) != 1UL) if (BinaryGcdGpu(n, m) != 1UL)
{ {
results[index] = 0; results[index] = 0;
return; return;
} }
}
long len = smallPrimes.Length; long len = smallPrimes.Length;
for (int i = 0; i < len; i++) for (int i = 0; i < len; i++)