dmidrange.c (1724B)
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/dmidrange.h" 20 #include "stdlib/math/base/assert/is_nan.h" 21 #include "stdlib/math/base/assert/is_positive_zero.h" 22 #include "stdlib/math/base/assert/is_negative_zero.h" 23 #include <stdint.h> 24 25 /** 26 * Computes the mid-range of a double-precision floating-point strided array. 27 * 28 * @param N number of indexed elements 29 * @param X input array 30 * @param stride stride length 31 * @return output value 32 */ 33 double stdlib_strided_dmidrange( const int64_t N, const double *X, const int64_t stride ) { 34 double max; 35 double min; 36 int64_t ix; 37 int64_t i; 38 double v; 39 40 if ( N <= 0 ) { 41 return 0.0 / 0.0; // NaN 42 } 43 if ( N == 1 || stride == 0 ) { 44 return X[ 0 ]; 45 } 46 if ( stride < 0 ) { 47 ix = (1-N) * stride; 48 } else { 49 ix = 0; 50 } 51 min = X[ ix ]; 52 max = min; 53 for ( i = 1; i < N; i++ ) { 54 ix += stride; 55 v = X[ ix ]; 56 if ( stdlib_base_is_nan( v ) ) { 57 return v; 58 } 59 if ( v < min || ( v == min && stdlib_base_is_negative_zero( v ) ) ) { 60 min = v; 61 } else if ( v > max || ( v == max && stdlib_base_is_positive_zero( v ) ) ) { 62 max = v; 63 } 64 } 65 return ( max+min ) / 2.0; 66 }