main.c

/**
* @license Apache-2.0
*
* Copyright (c) 2022 The Stdlib Authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
*    http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/

#include "stdlib/math/base/special/fibonacci.h"
#include "stdlib/constants/float64/max_safe_nth_fibonacci.h"

static const int64_t fibonacci_value[ 79 ] = {
	0,
	1,
	1,
	2,
	3,
	5,
	8,
	13,
	21,
	34,
	55,
	89,
	144,
	233,
	377,
	610,
	987,
	1597,
	2584,
	4181,
	6765,
	10946,
	17711,
	28657,
	46368,
	75025,
	121393,
	196418,
	317811,
	514229,
	832040,
	1346269,
	2178309,
	3524578,
	5702887,
	9227465,
	14930352,
	24157817,
	39088169,
	63245986,
	102334155,
	165580141,
	267914296,
	433494437,
	701408733,
	1134903170,
	1836311903,
	2971215073,
	4807526976,
	7778742049,
	12586269025,
	20365011074,
	32951280099,
	53316291173,
	86267571272,
	139583862445,
	225851433717,
	365435296162,
	591286729879,
	956722026041,
	1548008755920,
	2504730781961,
	4052739537881,
	6557470319842,
	10610209857723,
	17167680177565,
	27777890035288,
	44945570212853,
	72723460248141,
	117669030460994,
	190392490709135,
	308061521170129,
	498454011879264,
	806515533049393,
	1304969544928657,
	2111485077978050,
	3416454622906707,
	5527939700884757,
	8944394323791464
};

/**
* Computes the nth Fibonacci number.
*
* @param n    input value
* @return     output value
*
* @example
* double out = stdlib_base_fibonacci( 1 );
* // returns 1
*/
double stdlib_base_fibonacci( const int32_t n ) {
	if ( n < 0 || n > STDLIB_CONSTANT_FLOAT64_MAX_SAFE_NTH_FIBONACCI ) {
		return 0.0 / 0.0; // NaN
	}
	return fibonacci_value[ n ];
}