dcusumors.c (1499B)
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/dcusumors.h" 20 #include <stdint.h> 21 22 /** 23 * Computes the cumulative sum of double-precision floating-point strided array elements using ordinary recursive summation. 24 * 25 * @param N number of indexed elements 26 * @param sum initial sum 27 * @param X input array 28 * @param strideX X stride length 29 * @param Y output array 30 * @param strideY Y stride length 31 */ 32 void stdlib_strided_dcusumors( const int64_t N, const double sum, const double *X, const int64_t strideX, double *Y, const int64_t strideY ) { 33 int64_t ix; 34 int64_t iy; 35 int64_t i; 36 double s; 37 38 if ( N <= 0 ) { 39 return; 40 } 41 if ( strideX < 0 ) { 42 ix = (1-N) * strideX; 43 } else { 44 ix = 0; 45 } 46 if ( strideY < 0 ) { 47 iy = (1-N) * strideY; 48 } else { 49 iy = 0; 50 } 51 s = sum; 52 for ( i = 0; i < N; i++ ) { 53 s += X[ ix ]; 54 Y[ iy ] = s; 55 ix += strideX; 56 iy += strideY; 57 } 58 return; 59 }