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chore: fix comments & follow stdlib's conventions
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‎lib/node_modules/@stdlib/math/base/special/digammaf/lib/main.js‎

Lines changed: 91 additions & 42 deletions
Original file line numberDiff line numberDiff line change
@@ -14,27 +14,79 @@
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*
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*
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* ## Notice
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*
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* The original C code, long comment, copyright, license, and constants are from [Cephes]{@link http://www.netlib.org/cephes}. The implementation follows the original, but has been modified for JavaScript.
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*
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* ```text
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* Cephes Math Library Release 2.2: June, 1992
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* Copyright 1984, 1987, 1992 by Stephen L. Moshier
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* Direct inquiries to 30 Frost Street, Cambridge, MA 02140
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* ```
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*/
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'use strict';
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2132
// MODULES //
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23-
var float64ToFloat32 = require( '@stdlib/number/float64/base/to-float32' );
34+
var f32 = require( '@stdlib/number/float64/base/to-float32' );
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var floorf = require( '@stdlib/math/base/special/floorf' );
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var lnf = require( '@stdlib/math/base/special/lnf' );
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var cotf = require( '@stdlib/math/base/special/cotf' );
37+
var tanf = require( '@stdlib/math/base/special/tanf' );
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var FLOAT32_PI = require( '@stdlib/constants/float32/pi' );
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var EULERGAMMA = require( '@stdlib/constants/float32/eulergamma' );
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var isnanf = require( '@stdlib/math/base/assert/is-nanf' );
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var polyvalP = require( './polyval_p.js' );
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// VARIABLES //
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// Threshold above which the asymptotic expansion's correction term is below float32 epsilon:
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var ASYMPTOTIC_THRESHOLD = 1.0e8;
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// Minimum value of x for which we use the asymptotic expansion directly:
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var MIN_SAFE_ASYMPTOTIC = 10.0;
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// MAIN //
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/**
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* Evaluates the digamma function for a single-precision floating-point number.
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*
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* ## Method
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*
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* 1. For \\\\(x \u003c= 0\\\\), we use the reflection formula
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*
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* ```tex
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* \\psi(1-x) = \\psi(x) + \\frac{\\pi}{\\tan(\\pi \\cdot x)}
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* ```
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*
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* to make \\\\(x\\\\) positive.
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*
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* 2. For positive integer \\\\(x \u003c= 10\\\\), we use the recurrence
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*
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* ```tex
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* \\psi(n) = -\\gamma + \\sum_{k=1}^{n-1} \\frac{1}{k}
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* ```
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*
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* where \\\\(\\gamma\\\\) is the Euler-Mascheroni constant.
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*
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* 3. For general \\\\(x\\\\), we apply the recurrence relation
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*
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* ```tex
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* \\psi(x+1) = \\psi(x) + \\frac{1}{x}
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* ```
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*
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* until \\\\(x \u003e= 10\\\\), then use the asymptotic expansion
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*
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* ```tex
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* \\psi(x) = \\ln(x) - \\frac{1}{2x} - \\sum_{k=1}^{\\infty} \\frac{B_{2k}}{2k x^{2k}}
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* ```
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*
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* where \\\\(B_{2k}\\\\) are Bernoulli numbers.
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*
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* @param {number} x - input value
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* @returns {number} function value
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*
@@ -64,19 +116,17 @@ var polyvalP = require( './polyval_p.js' );
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*/
65117
function digammaf(x) {
66118
var negative;
67-
var nz;
119+
var tmp;
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var rem;
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var xx;
69-
var p;
70-
var q;
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var s;
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var w;
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var y;
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var z;
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var i;
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var n;
77128

78-
xx = float64ToFloat32(x);
79-
nz = 0.0;
129+
xx = f32(x);
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negative = false;
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82132
if (isnanf(xx)) {
@@ -86,58 +136,57 @@ function digammaf(x) {
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// Handle negative arguments using reflection formula...
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if (xx <= 0.0) {
88138
negative = true;
89-
q = xx;
90-
p = floorf(q);
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140+
// Argument reduction for tan:
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rem = f32(xx - floorf(xx));
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143+
// Reflect:
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xx = f32(1.0 - xx);
91145

92146
// Check for singularity (negative integer or zero)...
93-
if (p === q) {
147+
if (rem === 0.0) {
94148
return NaN;
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}
96-
97-
// Compute fractional part...
98-
nz = float64ToFloat32(q - p);
99-
if (nz === 0.5) {
100-
nz = 0.0;
101-
} else {
102-
if (nz > 0.5) {
103-
p += 1.0;
104-
nz = float64ToFloat32(q - p);
105-
}
106-
nz = float64ToFloat32(FLOAT32_PI * cotf(float64ToFloat32(FLOAT32_PI * nz))); // eslint-disable-line max-len
150+
if (rem > 0.5) {
151+
rem = f32(rem - 1.0);
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}
108-
xx = float64ToFloat32(1.0 - xx);
153+
tmp = f32(FLOAT32_PI / tanf(f32(FLOAT32_PI * rem)));
154+
} else {
155+
tmp = 0.0;
109156
}
110157

111158
// Use direct formula for small positive integers...
112-
if (xx <= 10.0 && xx === floorf(xx)) {
159+
if (xx <= MIN_SAFE_ASYMPTOTIC && xx === floorf(xx)) {
113160
y = 0.0;
114161
n = xx;
115162
for (i = 1; i < n; i++) {
116-
w = i;
117-
y = float64ToFloat32(y + float64ToFloat32(1.0 / w));
163+
y = f32(y + f32(1.0 / i));
118164
}
119-
y = float64ToFloat32(y - EULERGAMMA);
120-
} else {
121-
// Use recurrence to make x large enough for asymptotic expansion...
122-
s = xx;
123-
w = 0.0;
124-
while (s < 10.0) {
125-
w = float64ToFloat32(w + float64ToFloat32(1.0 / s));
126-
s = float64ToFloat32(s + 1.0);
165+
y = f32(y - EULERGAMMA);
166+
if (negative) {
167+
y = f32(y - tmp);
127168
}
169+
return y;
170+
}
128171

129-
// Asymptotic expansion...
130-
if (s < 1.0e8) {
131-
z = float64ToFloat32(1.0 / float64ToFloat32(s * s));
132-
y = float64ToFloat32(z * polyvalP(z));
133-
} else {
134-
y = 0.0;
135-
}
136-
y = float64ToFloat32(lnf(s) - float64ToFloat32(0.5 / s) - y - w);
172+
// Use recurrence to make x large enough for asymptotic expansion...
173+
s = xx;
174+
w = 0.0;
175+
while (s < MIN_SAFE_ASYMPTOTIC) {
176+
w = f32(w + f32(1.0 / s));
177+
s = f32(s + 1.0);
137178
}
138179

180+
// Asymptotic expansion...
181+
if (s < ASYMPTOTIC_THRESHOLD) {
182+
z = f32(1.0 / f32(s * s));
183+
y = f32(z * polyvalP(z));
184+
} else {
185+
y = 0.0;
186+
}
187+
y = f32(lnf(s) - f32(0.5 / s) - y - w);
139188
if (negative) {
140-
y = float64ToFloat32(y - nz);
189+
y = f32(y - tmp);
141190
}
142191
return y;
143192
}

‎lib/node_modules/@stdlib/math/base/special/digammaf/src/Makefile‎

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@@ -0,0 +1,70 @@
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#/
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# @license Apache-2.0
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#
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# Copyright (c) 2026 The Stdlib Authors.
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
13+
# distributed under the License is distributed on an "AS IS" BASIS,
14+
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
15+
# See the License for the specific language governing permissions and
16+
# limitations under the License.
17+
#/
18+
19+
# VARIABLES #
20+
21+
ifndef VERBOSE
22+
QUIET := @
23+
else
24+
QUIET :=
25+
endif
26+
27+
# Determine the OS ([1][1], [2][2]).
28+
#
29+
# [1]: https://en.wikipedia.org/wiki/Uname#Examples
30+
# [2]: http://stackoverflow.com/a/27776822/2225624
31+
OS ?= $(shell uname)
32+
ifneq (, $(findstring MINGW,$(OS)))
33+
OS := WINNT
34+
else
35+
ifneq (, $(findstring MSYS,$(OS)))
36+
OS := WINNT
37+
else
38+
ifneq (, $(findstring CYGWIN,$(OS)))
39+
OS := WINNT
40+
else
41+
ifneq (, $(findstring Windows_NT,$(OS)))
42+
OS := WINNT
43+
endif
44+
endif
45+
endif
46+
endif
47+
48+
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# RULES #
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#/
52+
# Removes generated files for building an add-on.
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#
54+
# @example
55+
# make clean-addon
56+
#/
57+
clean-addon:
58+
$(QUIET) -rm -f *.o *.node
59+
60+
.PHONY: clean-addon
61+
62+
#/
63+
# Removes generated files.
64+
#
65+
# @example
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# make clean
67+
#/
68+
clean: clean-addon
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.PHONY: clean

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