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// Copyright (c) 2019-2021 Alexander Medvednikov. All rights reserved.
// Use of this source code is governed by an MIT license
// that can be found in the LICENSE file.
module math
// aprox_sin returns an approximation of sin(a) made using lolremez
pub fn aprox_sin(a f64) f64 {
a0 := 1.91059300966915117e-31
a1 := 1.00086760103908896
a2 := -1.21276126894734565e-2
a3 := -1.38078780785773762e-1
a4 := -2.67353392911981221e-2
a5 := 2.08026600266304389e-2
a6 := -3.03996055049204407e-3
a7 := 1.38235642404333740e-4
return a0 + a * (a1 + a * (a2 + a * (a3 + a * (a4 + a * (a5 + a * (a6 + a * a7))))))
}
// aprox_cos returns an approximation of sin(a) made using lolremez
pub fn aprox_cos(a f64) f64 {
a0 := 9.9995999154986614e-1
a1 := 1.2548995793001028e-3
a2 := -5.0648546280678015e-1
a3 := 1.2942246466519995e-2
a4 := 2.8668384702547972e-2
a5 := 7.3726485210586547e-3
a6 := -3.8510875386947414e-3
a7 := 4.7196604604366623e-4
a8 := -1.8776444013090451e-5
return a0 + a * (a1 + a * (a2 + a * (a3 + a * (a4 + a * (a5 + a * (a6 + a * (a7 + a * a8)))))))
}
// copysign returns a value with the magnitude of x and the sign of y
[inline]
pub fn copysign(x f64, y f64) f64 {
return f64_from_bits((f64_bits(x) & ~sign_mask) | (f64_bits(y) & sign_mask))
}
// degrees convert from degrees to radians.
[inline]
pub fn degrees(radians f64) f64 {
return radians * (180.0 / pi)
}
// digits returns an array of the digits of n in the given base.
pub fn digits(_n int, base int) []int {
if base < 2 {
panic('digits: Cannot find digits of n with base $base')
}
mut n := _n
mut sign := 1
if n < 0 {
sign = -1
n = -n
}
mut res := []int{}
for n != 0 {
res << (n % base) * sign
n /= base
}
return res
}
// max returns the maximum value of the two provided.
[inline]
pub fn max(a f64, b f64) f64 {
if a > b {
return a
}
return b
}
// min returns the minimum value of the two provided.
[inline]
pub fn min(a f64, b f64) f64 {
if a < b {
return a
}
return b
}
// minmax returns the minimum and maximum value of the two provided.
pub fn minmax(a f64, b f64) (f64, f64) {
if a < b {
return a, b
}
return b, a
}
// sign returns the corresponding sign -1.0, 1.0 of the provided number.
// if n is not a number, its sign is nan too.
[inline]
pub fn sign(n f64) f64 {
if is_nan(n) {
return nan()
}
return copysign(1.0, n)
}
// signi returns the corresponding sign -1.0, 1.0 of the provided number.
[inline]
pub fn signi(n f64) int {
return int(copysign(1.0, n))
}
// radians convert from radians to degrees.
[inline]
pub fn radians(degrees f64) f64 {
return degrees * (pi / 180.0)
}
// signbit returns a value with the boolean representation of the sign for x
[inline]
pub fn signbit(x f64) bool {
return f64_bits(x) & sign_mask != 0
}
pub fn tolerance(a f64, b f64, tol f64) bool {
mut ee := tol
// Multiplying by ee here can underflow denormal values to zero.
// Check a==b so that at least if a and b are small and identical
// we say they match.
if a == b {
return true
}
mut d := a - b
if d < 0 {
d = -d
}
// note: b is correct (expected) value, a is actual value.
// make error tolerance a fraction of b, not a.
if b != 0 {
ee = ee * b
if ee < 0 {
ee = -ee
}
}
return d < ee
}
pub fn close(a f64, b f64) bool {
return tolerance(a, b, 1e-14)
}
pub fn veryclose(a f64, b f64) bool {
return tolerance(a, b, 4e-16)
}
pub fn alike(a f64, b f64) bool {
if is_nan(a) && is_nan(b) {
return true
} else if a == b {
return signbit(a) == signbit(b)
}
return false
}
fn is_odd_int(x f64) bool {
xi, xf := modf(x)
return xf == 0 && (i64(xi) & 1) == 1
}
fn is_neg_int(x f64) bool {
if x < 0 {
_, xf := modf(x)
return xf == 0
}
return false
}
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