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| 1 | +<!-- |
| 2 | +
|
| 3 | +@license Apache-2.0 |
| 4 | +
|
| 5 | +Copyright (c) 2025 The Stdlib Authors. |
| 6 | +
|
| 7 | +Licensed under the Apache License, Version 2.0 (the "License"); |
| 8 | +you may not use this file except in compliance with the License. |
| 9 | +You may obtain a copy of the License at |
| 10 | +
|
| 11 | + http://www.apache.org/licenses/LICENSE-2.0 |
| 12 | +
|
| 13 | +Unless required by applicable law or agreed to in writing, software |
| 14 | +distributed under the License is distributed on an "AS IS" BASIS, |
| 15 | +WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 16 | +See the License for the specific language governing permissions and |
| 17 | +limitations under the License. |
| 18 | +
|
| 19 | +--> |
| 20 | + |
| 21 | +# Fibonaccif |
| 22 | + |
| 23 | +> Compute the nth [Fibonacci number][fibonacci-number] as a single-precision floating-point number. |
| 24 | +
|
| 25 | +<section class="intro"> |
| 26 | + |
| 27 | +The [Fibonacci numbers][fibonacci-number] are the integer sequence |
| 28 | + |
| 29 | +<!-- <equation class="equation" label="eq:fibonacci_sequence" align="center" raw="0, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89, 144, \ldots" alt="Fibonacci sequence"> --> |
| 30 | + |
| 31 | +```math |
| 32 | +0, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89, 144, \ldots |
| 33 | +``` |
| 34 | + |
| 35 | +<!-- </equation> --> |
| 36 | + |
| 37 | +The sequence is defined by the recurrence relation |
| 38 | + |
| 39 | +<!-- <equation class="equation" label="eq:fibonacci_recurrence_relation" align="center" raw="F_n = F_{n-1} + F_{n-2}" alt="Fibonacci sequence recurrence relation"> --> |
| 40 | + |
| 41 | +```math |
| 42 | +F_n = F_{n-1} + F_{n-2} |
| 43 | +``` |
| 44 | + |
| 45 | +<!-- </equation> --> |
| 46 | + |
| 47 | +with seed values `F_0 = 0` and `F_1 = 1`. |
| 48 | + |
| 49 | +</section> |
| 50 | + |
| 51 | +<!-- /.intro --> |
| 52 | + |
| 53 | +<section class="usage"> |
| 54 | + |
| 55 | +## Usage |
| 56 | + |
| 57 | +```javascript |
| 58 | +var fibonaccif = require( '@stdlib/math/base/special/fibonaccif' ); |
| 59 | +``` |
| 60 | + |
| 61 | +#### fibonaccif( n ) |
| 62 | + |
| 63 | +Computes the nth [Fibonacci number][fibonacci-number] as a single-precision floating-point number. |
| 64 | + |
| 65 | +```javascript |
| 66 | +var v = fibonaccif( 0 ); |
| 67 | +// returns 0 |
| 68 | + |
| 69 | +v = fibonaccif( 1 ); |
| 70 | +// returns 1 |
| 71 | + |
| 72 | +v = fibonaccif( 2 ); |
| 73 | +// returns 1 |
| 74 | + |
| 75 | +v = fibonaccif( 3 ); |
| 76 | +// returns 2 |
| 77 | + |
| 78 | +v = fibonaccif( 36 ); |
| 79 | +// returns 14930352 |
| 80 | +``` |
| 81 | + |
| 82 | +If `n > 36`, the function returns `NaN`, as larger [Fibonacci numbers][fibonacci-number] cannot be safely represented in [single-precision floating-point format][ieee754]. |
| 83 | + |
| 84 | +```javascript |
| 85 | +var v = fibonaccif( 37 ); |
| 86 | +// returns NaN |
| 87 | +``` |
| 88 | + |
| 89 | +If not provided a nonnegative integer value, the function returns `NaN`. |
| 90 | + |
| 91 | +```javascript |
| 92 | +var v = fibonaccif( 3.14 ); |
| 93 | +// returns NaN |
| 94 | + |
| 95 | +v = fibonaccif( -1 ); |
| 96 | +// returns NaN |
| 97 | +``` |
| 98 | + |
| 99 | +If provided `NaN`, the function returns `NaN`. |
| 100 | + |
| 101 | +```javascript |
| 102 | +var v = fibonaccif( NaN ); |
| 103 | +// returns NaN |
| 104 | +``` |
| 105 | + |
| 106 | +</section> |
| 107 | + |
| 108 | +<!-- /.usage --> |
| 109 | + |
| 110 | +<section class="notes"> |
| 111 | + |
| 112 | +</section> |
| 113 | + |
| 114 | +<!-- /.notes --> |
| 115 | + |
| 116 | +<section class="examples"> |
| 117 | + |
| 118 | +## Examples |
| 119 | + |
| 120 | +<!-- eslint no-undef: "error" --> |
| 121 | + |
| 122 | +```javascript |
| 123 | +var discreteUniform = require( '@stdlib/random/array/discrete-uniform' ); |
| 124 | +var logEachMap = require( '@stdlib/console/log-each-map' ); |
| 125 | +var fibonaccif = require( '@stdlib/math/base/special/fibonaccif' ); |
| 126 | + |
| 127 | +var x = discreteUniform( 10, 0, 36 ); |
| 128 | + |
| 129 | +logEachMap( 'fibonaccif(%d) = %0.1f', x, fibonaccif ); |
| 130 | +``` |
| 131 | + |
| 132 | +</section> |
| 133 | + |
| 134 | +<!-- /.examples --> |
| 135 | + |
| 136 | +<!-- C interface documentation. --> |
| 137 | + |
| 138 | +* * * |
| 139 | + |
| 140 | +<section class="c"> |
| 141 | + |
| 142 | +## C APIs |
| 143 | + |
| 144 | +<!-- Section to include introductory text. Make sure to keep an empty line after the intro `section` element and another before the `/section` close. --> |
| 145 | + |
| 146 | +<section class="intro"> |
| 147 | + |
| 148 | +</section> |
| 149 | + |
| 150 | +<!-- /.intro --> |
| 151 | + |
| 152 | +<!-- C usage documentation. --> |
| 153 | + |
| 154 | +<section class="usage"> |
| 155 | + |
| 156 | +### Usage |
| 157 | + |
| 158 | +```c |
| 159 | +#include "stdlib/math/base/special/fibonaccif.h" |
| 160 | +``` |
| 161 | + |
| 162 | +#### stdlib_base_fibonaccif( n ) |
| 163 | + |
| 164 | +Computes the nth [Fibonacci number][fibonacci-number] as a single-precision floating-point number. |
| 165 | + |
| 166 | +```c |
| 167 | +float out = stdlib_base_fibonaccif( 0 ); |
| 168 | +// returns 0.0f |
| 169 | + |
| 170 | +out = stdlib_base_fibonaccif( 1 ); |
| 171 | +// returns 1.0f |
| 172 | +``` |
| 173 | + |
| 174 | +The function accepts the following arguments: |
| 175 | + |
| 176 | +- **n**: `[in] int32_t` input value. |
| 177 | + |
| 178 | +```c |
| 179 | +float stdlib_base_fibonacci( const int32_t n ); |
| 180 | +``` |
| 181 | +
|
| 182 | +</section> |
| 183 | +
|
| 184 | +<!-- /.usage --> |
| 185 | +
|
| 186 | +<!-- C API usage notes. Make sure to keep an empty line after the `section` element and another before the `/section` close. --> |
| 187 | +
|
| 188 | +<section class="notes"> |
| 189 | +
|
| 190 | +</section> |
| 191 | +
|
| 192 | +<!-- /.notes --> |
| 193 | +
|
| 194 | +<!-- C API usage examples. --> |
| 195 | +
|
| 196 | +<section class="examples"> |
| 197 | +
|
| 198 | +### Examples |
| 199 | +
|
| 200 | +```c |
| 201 | +#include "stdlib/math/base/special/fibonaccif.h" |
| 202 | +#include <stdio.h> |
| 203 | +#include <stdint.h> |
| 204 | +
|
| 205 | +int main( void ) { |
| 206 | + int32_t i; |
| 207 | + float v; |
| 208 | +
|
| 209 | + for ( i = 0; i < 37; i++ ) { |
| 210 | + v = stdlib_base_fibonaccif( i ); |
| 211 | + printf( "fibonaccif(%d) = %f\n", i, v ); |
| 212 | + } |
| 213 | +} |
| 214 | +``` |
| 215 | + |
| 216 | +</section> |
| 217 | + |
| 218 | +<!-- /.examples --> |
| 219 | + |
| 220 | +</section> |
| 221 | + |
| 222 | +<!-- /.c --> |
| 223 | + |
| 224 | +<!-- Section for related `stdlib` packages. Do not manually edit this section, as it is automatically populated. --> |
| 225 | + |
| 226 | +<section class="related"> |
| 227 | + |
| 228 | +</section> |
| 229 | + |
| 230 | +<!-- /.related --> |
| 231 | + |
| 232 | +<!-- Section for all links. Make sure to keep an empty line after the `section` element and another before the `/section` close. --> |
| 233 | + |
| 234 | +<section class="links"> |
| 235 | + |
| 236 | +[fibonacci-number]: https://en.wikipedia.org/wiki/Fibonacci_number |
| 237 | + |
| 238 | +[ieee754]: https://en.wikipedia.org/wiki/IEEE_754-1985 |
| 239 | + |
| 240 | +<!-- <related-links> --> |
| 241 | + |
| 242 | +<!-- </related-links> --> |
| 243 | + |
| 244 | +</section> |
| 245 | + |
| 246 | +<!-- /.links --> |
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