50 lines
1.0 KiB
V
50 lines
1.0 KiB
V
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module math
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// sinh calculates hyperbolic sine.
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pub fn sinh(x_ f64) f64 {
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mut x := x_
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// The coefficients are #2029 from Hart & Cheney. (20.36D)
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p0 := -0.6307673640497716991184787251e+6
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p1 := -0.8991272022039509355398013511e+5
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p2 := -0.2894211355989563807284660366e+4
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p3 := -0.2630563213397497062819489e+2
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q0 := -0.6307673640497716991212077277e+6
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q1 := 0.1521517378790019070696485176e+5
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q2 := -0.173678953558233699533450911e+3
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mut sign := false
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if x < 0 {
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x = -x
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sign = true
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}
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mut temp := 0.0
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if x > 21 {
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temp = exp(x) * 0.5
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} else if x > 0.5 {
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ex := exp(x)
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temp = (ex - 1.0 / ex) * 0.5
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} else {
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sq := x * x
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temp = (((p3 * sq + p2) * sq + p1) * sq + p0) * x
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temp = temp / (((sq + q2) * sq + q1) * sq + q0)
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}
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if sign {
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temp = -temp
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}
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return temp
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}
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// cosh returns the hyperbolic cosine of x.
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//
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// special cases are:
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// cosh(±0) = 1
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// cosh(±inf) = +inf
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// cosh(nan) = nan
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pub fn cosh(x f64) f64 {
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abs_x := abs(x)
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if abs_x > 21 {
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return exp(abs_x) * 0.5
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}
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ex := exp(abs_x)
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return (ex + 1.0 / ex) * 0.5
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}
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