drange.c (1551B)
1 /** 2 * @license Apache-2.0 3 * 4 * Copyright (c) 2020 The Stdlib Authors. 5 * 6 * Licensed under the Apache License, Version 2.0 (the "License"); 7 * you may not use this file except in compliance with the License. 8 * You may obtain a copy of the License at 9 * 10 * http://www.apache.org/licenses/LICENSE-2.0 11 * 12 * 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 #include "stdlib/stats/base/drange.h" 20 #include "stdlib/math/base/assert/is_nan.h" 21 #include <stdint.h> 22 23 /** 24 * Computes the range of a double-precision floating-point strided array. 25 * 26 * @param N number of indexed elements 27 * @param X input array 28 * @param stride stride length 29 * @return output value 30 */ 31 double stdlib_strided_drange( const int64_t N, const double *X, const int64_t stride ) { 32 double max; 33 double min; 34 int64_t ix; 35 int64_t i; 36 double v; 37 38 if ( N <= 0 ) { 39 return 0.0 / 0.0; // NaN 40 } 41 if ( N == 1 || stride == 0 ) { 42 if ( stdlib_base_is_nan( X[ 0 ] ) ) { 43 return X[ 0 ]; 44 } 45 return 0.0; 46 } 47 if ( stride < 0 ) { 48 ix = (1-N) * stride; 49 } else { 50 ix = 0; 51 } 52 min = X[ ix ]; 53 max = min; 54 for ( i = 1; i < N; i++ ) { 55 ix += stride; 56 v = X[ ix ]; 57 if ( stdlib_base_is_nan( v ) ) { 58 return v; 59 } 60 if ( v < min ) { 61 min = v; 62 } else if ( v > max ) { 63 max = v; 64 } 65 } 66 return max - min; 67 }