21 lines
432 B
Rust
21 lines
432 B
Rust
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#[inline]
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pub fn inverse_sqrt(n: f32) -> f32 {
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1f32 / n.sqrt()
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}
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union MixedIntFloat {
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f: f32,
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i: u32,
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}
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/// see https://en.wikipedia.org/wiki/Fast_inverse_square_root
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#[inline]
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pub fn fast_inverse_sqrt(n: f32) -> f32 {
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let mut conv: MixedIntFloat = MixedIntFloat { f: n };
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unsafe {
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conv.i = 0x5f3759df - (conv.i >> 1);
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conv.f *= 1.5f32 - (n * 0.5f32 * conv.f * conv.f);
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conv.f
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}
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}
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