/rust/registry/src/index.crates.io-1949cf8c6b5b557f/pic-scale-safe-0.1.10/src/math/kaiser.rs

Source
/*
 * Copyright (c) Radzivon Bartoshyk, 10/2024. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without modification,
 * are permitted provided that the following conditions are met:
 *
 * 1.  Redistributions of source code must retain the above copyright notice, this
 * list of conditions and the following disclaimer.
 *
 * 2.  Redistributions in binary form must reproduce the above copyright notice,
 * this list of conditions and the following disclaimer in the documentation
 * and/or other materials provided with the distribution.
 *
 * 3.  Neither the name of the copyright holder nor the names of its
 * contributors may be used to endorse or promote products derived from
 * this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

use num_traits::{AsPrimitive, Float};
use std::ops::{AddAssign, Div, Mul, MulAssign, Sub};

#[inline(always)]
pub(crate) fn bessel_i0<
    V: Copy + Mul<Output = V> + Div<Output = V> + MulAssign + AddAssign + 'static + PartialOrd,
>(
    x: V,
) -> V
where
    f64: AsPrimitive<V>,
{
    let mut s = 1.0.as_();
    let y = x * x / 4.0.as_();
    let mut t = y;
    let mut i: V = 2.0f64.as_();
    while t > 1e-12.as_() {
        s += t;
        t *= y / (i * i);
        i += 1f64.as_();
    }
    s
}

#[inline(always)]
pub(crate) fn kaiser<
    V: Copy
        + Mul<Output = V>
        + Div<Output = V>
        + MulAssign
        + AddAssign
        + 'static
        + PartialOrd
        + Sub<Output = V>
        + Float,
>(
    x: V,
) -> V
where
    f64: AsPrimitive<V>,
    f32: AsPrimitive<V>,
{
    if x > 1f32.as_() {
        return 0f32.as_();
    }
    let i0a = 1.0f64.as_() / bessel_i0(6.33f64.as_());
    bessel_i0(6.33f64.as_() * (1.0f64.as_() - x * x).sqrt()) * i0a
}

Coverage Report

Created: 2026-05-30 07:32

Line	Count	Source
1		/*
2		* Copyright (c) Radzivon Bartoshyk, 10/2024. All rights reserved.
3		*
4		* Redistribution and use in source and binary forms, with or without modification,
5		* are permitted provided that the following conditions are met:
6		*
7		* 1. Redistributions of source code must retain the above copyright notice, this
8		* list of conditions and the following disclaimer.
9		*
10		* 2. Redistributions in binary form must reproduce the above copyright notice,
11		* this list of conditions and the following disclaimer in the documentation
12		* and/or other materials provided with the distribution.
13		*
14		* 3. Neither the name of the copyright holder nor the names of its
15		* contributors may be used to endorse or promote products derived from
16		* this software without specific prior written permission.
17		*
18		* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
19		* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
20		* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
21		* DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
22		* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
23		* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
24		* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
25		* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
26		* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
27		* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
28		*/
29
30		use num_traits::{AsPrimitive, Float};
31		use std::ops::{AddAssign, Div, Mul, MulAssign, Sub};
32
33		#[inline(always)]
34	0	pub(crate) fn bessel_i0<
35	0	V: Copy + Mul<Output = V> + Div<Output = V> + MulAssign + AddAssign + 'static + PartialOrd,
36	0	>(
37	0	x: V,
38	0	) -> V
39	0	where
40	0	f64: AsPrimitive<V>,
41		{
42	0	let mut s = 1.0.as_();
43	0	let y = x * x / 4.0.as_();
44	0	let mut t = y;
45	0	let mut i: V = 2.0f64.as_();
46	0	while t > 1e-12.as_() {
47	0	s += t;
48	0	t = y / (i i);
49	0	i += 1f64.as_();
50	0	}
51	0	s
52	0	}
53
54		#[inline(always)]
55	0	pub(crate) fn kaiser<
56	0	V: Copy
57	0	+ Mul<Output = V>
58	0	+ Div<Output = V>
59	0	+ MulAssign
60	0	+ AddAssign
61	0	+ 'static
62	0	+ PartialOrd
63	0	+ Sub<Output = V>
64	0	+ Float,
65	0	>(
66	0	x: V,
67	0	) -> V
68	0	where
69	0	f64: AsPrimitive<V>,
70	0	f32: AsPrimitive<V>,
71		{
72	0	if x > 1f32.as_() {
73	0	return 0f32.as_();
74	0	}
75	0	let i0a = 1.0f64.as_() / bessel_i0(6.33f64.as_());
76	0	bessel_i0(6.33f64.as_() * (1.0f64.as_() - x * x).sqrt()) * i0a
77	0	}