refactor!: modify C implementation to accept double instead of int32 in math/base/special/fibonacci

This commit updates the signature of the C API to accept a double rather than int32. The rationale was so that users get the same results/behavior in both JavaScript and C. This arose in the context of ufuncs, where the diverging type signatures meant differences in what dtypes would be permissible. Instead, we decided to unify and ensure the behavior is consistent.

BREAKING CHANGE: update signature to accept doubles

User code should behave similarly in the primary case of providing integer-valued input values. However, no longer will real-values truncate. Now, real-valued inputs will result in `NaN`, which is, arguably, better behavior, as real-to-integer truncation can be a source of silent bugs.

PR-URL: #7923
Reviewed-by: Athan Reines <[email protected]>

Author: gunjjoshi

lib/node_modules/@stdlib/math/base/special/fibonacci/README.md

@@ -185,10 +185,10 @@ out = stdlib_base_fibonacci( 1 );
 
 The function accepts the following arguments:
 
--   **n**: `[in] int32_t` input value.
+-   **n**: `[in] double` input value.
 
 ```c
-double stdlib_base_fibonacci( const int32_t n );
+double stdlib_base_fibonacci( const double n );
 ```
 
 </section>
@@ -212,15 +212,14 @@ double stdlib_base_fibonacci( const int32_t n );
 ```c
 #include "stdlib/math/base/special/fibonacci.h"
 #include <stdio.h>
-#include <stdint.h>
 
 int main( void ) {
-    int32_t i;
+    double i;
     double v;
 
-    for ( i = 0; i < 79; i++ ) {
+    for ( i = 0.0; i < 79.0; i++ ) {
         v = stdlib_base_fibonacci( i );
-        printf( "fibonacci(%d) = %lf\n", i, v );
+        printf( "fibonacci(%lf) = %lf\n", i, v );
     }
 }
 ```

lib/node_modules/@stdlib/math/base/special/fibonacci/benchmark/c/native/benchmark.c

@@ -91,13 +91,13 @@ static double rand_double( void ) {
 */
 static double benchmark( void ) {
 	double elapsed;
-	int32_t x[ 100 ];
+	double x[ 100 ];
 	double t;
 	double y;
 	int i;
 
 	for ( i = 0; i < 100; i++ ) {
-		x[ i ] = (int32_t)floor( 40.0*rand_double() );
+		x[ i ] = floor( 40.0*rand_double() );
 	}
 
 	t = tic();

lib/node_modules/@stdlib/math/base/special/fibonacci/examples/c/example.c

@@ -18,14 +18,13 @@
 
 #include "stdlib/math/base/special/fibonacci.h"
 #include <stdio.h>
-#include <stdint.h>
 
 int main( void ) {
-	int32_t i;
+	double i;
 	double v;
 
-	for ( i = 0; i < 79; i++ ) {
+	for ( i = 0.0; i < 79.0; i++ ) {
 		v = stdlib_base_fibonacci( i );
-		printf( "fibonacci(%d) = %lf\n", i, v );
+		printf( "fibonacci(%lf) = %lf\n", i, v );
 	}
 }

lib/node_modules/@stdlib/math/base/special/fibonacci/include/stdlib/math/base/special/fibonacci.h

@@ -19,8 +19,6 @@
 #ifndef STDLIB_MATH_BASE_SPECIAL_FIBONACCI_H
 #define STDLIB_MATH_BASE_SPECIAL_FIBONACCI_H
 
-#include <stdint.h>
-
 /*
 * If C++, prevent name mangling so that the compiler emits a binary file having undecorated names, thus mirroring the behavior of a C compiler.
 */
@@ -31,7 +29,7 @@ extern "C" {
 /**
 * Computes the nth Fibonacci number.
 */
-double stdlib_base_fibonacci( const int32_t n );
+double stdlib_base_fibonacci( const double n );
 
 #ifdef __cplusplus
 }

lib/node_modules/@stdlib/math/base/special/fibonacci/lib/main.js

@@ -21,7 +21,7 @@
 // MODULES //
 
 var isnan = require( '@stdlib/math/base/assert/is-nan' );
-var isInteger = require( '@stdlib/math/base/assert/is-integer' );
+var isNonnegativeInteger = require( '@stdlib/math/base/assert/is-nonnegative-integer' );
 var MAX_FIBONACCI = require( '@stdlib/constants/float64/max-safe-nth-fibonacci' );
 var FIBONACCI = require( './fibonacci.json' );
 
@@ -77,8 +77,7 @@ var FIBONACCI = require( './fibonacci.json' );
 function fibonacci( n ) {
 	if (
 		isnan( n ) ||
-		isInteger( n ) === false ||
-		n < 0 ||
+		!isNonnegativeInteger( n ) ||
 		n > MAX_FIBONACCI
 	) {
 		return NaN;

lib/node_modules/@stdlib/math/base/special/fibonacci/manifest.json

@@ -37,7 +37,8 @@
       "libpath": [],
       "dependencies": [
         "@stdlib/math/base/napi/unary",
-        "@stdlib/constants/float64/max-safe-nth-fibonacci"
+        "@stdlib/constants/float64/max-safe-nth-fibonacci",
+        "@stdlib/math/base/assert/is-nonnegative-integer"
       ]
     },
     {
@@ -51,7 +52,8 @@
       "libraries": [],
       "libpath": [],
       "dependencies": [
-        "@stdlib/constants/float64/max-safe-nth-fibonacci"
+        "@stdlib/constants/float64/max-safe-nth-fibonacci",
+        "@stdlib/math/base/assert/is-nonnegative-integer"
       ]
     },
     {
@@ -65,7 +67,8 @@
       "libraries": [],
       "libpath": [],
       "dependencies": [
-        "@stdlib/constants/float64/max-safe-nth-fibonacci"
+        "@stdlib/constants/float64/max-safe-nth-fibonacci",
+        "@stdlib/math/base/assert/is-nonnegative-integer"
       ]
     }
   ]

lib/node_modules/@stdlib/math/base/special/fibonacci/src/addon.c

@@ -19,4 +19,4 @@
 #include "stdlib/math/base/special/fibonacci.h"
 #include "stdlib/math/base/napi/unary.h"
 
-STDLIB_MATH_BASE_NAPI_MODULE_I_D( stdlib_base_fibonacci )
+STDLIB_MATH_BASE_NAPI_MODULE_D_D( stdlib_base_fibonacci )

lib/node_modules/@stdlib/math/base/special/fibonacci/src/main.c

@@ -18,6 +18,9 @@
 
 #include "stdlib/math/base/special/fibonacci.h"
 #include "stdlib/constants/float64/max_safe_nth_fibonacci.h"
+#include "stdlib/math/base/assert/is_nonnegative_integer.h"
+#include <stdint.h>
+#include <stdlib.h>
 
 static const int64_t fibonacci_value[ 79 ] = {
 	0,
@@ -108,12 +111,12 @@ static const int64_t fibonacci_value[ 79 ] = {
 * @return     output value
 *
 * @example
-* double out = stdlib_base_fibonacci( 1 );
-* // returns 1
+* double out = stdlib_base_fibonacci( 1.0 );
+* // returns 1.0
 */
-double stdlib_base_fibonacci( const int32_t n ) {
-	if ( n < 0 || n > STDLIB_CONSTANT_FLOAT64_MAX_SAFE_NTH_FIBONACCI ) {
+double stdlib_base_fibonacci( const double n ) {
+	if ( !stdlib_base_is_nonnegative_integer( n ) || n > STDLIB_CONSTANT_FLOAT64_MAX_SAFE_NTH_FIBONACCI ) {
 		return 0.0 / 0.0; // NaN
 	}
-	return fibonacci_value[ n ];
+	return fibonacci_value[ (size_t)n ];
 }