dnanasumors.c (1574B)
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/blas/ext/base/dnanasumors.h" 20 #include "stdlib/math/base/assert/is_nan.h" 21 #include <stdint.h> 22 #include <math.h> 23 24 /** 25 * Computes the sum of absolute values (L1 norm) of double-precision floating-point strided array elements, ignoring `NaN` values and using ordinary recursive summation. 26 * 27 * @param N number of indexed elements 28 * @param X input array 29 * @param stride stride length 30 * @return output value 31 */ 32 double stdlib_strided_dnanasumors( const int64_t N, const double *X, const int64_t stride ) { 33 double sum; 34 int64_t ix; 35 int64_t i; 36 double v; 37 38 if ( N <= 0 ) { 39 return 0.0; 40 } 41 if ( N == 1 || stride == 0 ) { 42 if ( stdlib_base_is_nan( X[ 0 ] ) ) { 43 return 0.0; 44 } 45 return fabs( X[ 0 ] ); 46 } 47 if ( stride < 0 ) { 48 ix = (1-N) * stride; 49 } else { 50 ix = 0; 51 } 52 sum = 0.0; 53 for ( i = 0; i < N; i++ ) { 54 v = X[ ix ]; 55 if ( !stdlib_base_is_nan( v ) ) { 56 sum += fabs( v ); 57 } 58 ix += stride; 59 } 60 return sum; 61 }