dcopy.f (3273B)
1 !> 2 ! @license Apache-2.0 3 ! 4 ! Copyright (c) 2018 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 !> Copies values from one vector to another vector. 20 ! 21 ! ## Notes 22 ! 23 ! * Modified version of reference BLAS level1 routine (version 3.7.0). Updated to "free form" Fortran 95. 24 ! 25 ! ## Authors 26 ! 27 ! * Univ. of Tennessee 28 ! * Univ. of California Berkeley 29 ! * Univ. of Colorado Denver 30 ! * NAG Ltd. 31 ! 32 ! ## History 33 ! 34 ! * Jack Dongarra, linpack, 3/11/78. 35 ! 36 ! - modified 12/3/93, array(1) declarations changed to array(*) 37 ! 38 ! ## License 39 ! 40 ! From <http://netlib.org/blas/faq.html>: 41 ! 42 ! > The reference BLAS is a freely-available software package. It is available from netlib via anonymous ftp and the World Wide Web. Thus, it can be included in commercial software packages (and has been). We only ask that proper credit be given to the authors. 43 ! > 44 ! > Like all software, it is copyrighted. It is not trademarked, but we do ask the following: 45 ! > 46 ! > * If you modify the source for these routines we ask that you change the name of the routine and comment the changes made to the original. 47 ! > 48 ! > * We will gladly answer any questions regarding the software. If a modification is done, however, it is the responsibility of the person who modified the routine to provide support. 49 ! 50 ! @param {integer} N - number of values to copy 51 ! @param {Array<double>} dx - input array 52 ! @param {integer} strideX - `dx` stride length 53 ! @param {Array<double>} dy - destination array 54 ! @param {integer} strideY - `dy` stride length 55 !< 56 subroutine dcopy( N, dx, strideX, dy, strideY ) 57 implicit none 58 ! .. 59 ! Scalar arguments: 60 integer :: strideX, strideY, N 61 ! .. 62 ! Array arguments: 63 double precision :: dx(*), dy(*) 64 ! .. 65 ! Local scalars: 66 integer :: mp1, ix, iy, i, m 67 ! .. 68 ! Intrinsic functions: 69 intrinsic mod 70 ! .. 71 if ( N <= 0 ) then 72 return 73 end if 74 ! .. 75 ! If both strides are equal to `1`, use unrolled loops... 76 if ( strideX == 1 .AND. strideY == 1 ) then 77 m = mod( N, 7 ) 78 ! .. 79 ! If we have a remainder, do a clean-up loop... 80 if ( m /= 0 ) then 81 do i = 1, m 82 dy( i ) = dx( i ) 83 end do 84 if ( N < 7 ) then 85 return 86 end if 87 end if 88 mp1 = m + 1 89 do i = mp1, N, 7 90 dy( i ) = dx( i ) 91 dy( i+1 ) = dx( i+1 ) 92 dy( i+2 ) = dx( i+2 ) 93 dy( i+3 ) = dx( i+3 ) 94 dy( i+4 ) = dx( i+4 ) 95 dy( i+5 ) = dx( i+5 ) 96 dy( i+6 ) = dx( i+6 ) 97 end do 98 else 99 if ( strideX < 0 ) then 100 ix = ((1-N)*strideX) + 1 101 else 102 ix = 1 103 end if 104 if ( strideY < 0 ) then 105 iy = ((1-N)*strideY) + 1 106 else 107 iy = 1 108 end if 109 do i = 1, N 110 dy( iy ) = dx( ix ) 111 ix = ix + strideX 112 iy = iy + strideY 113 end do 114 end if 115 return 116 end subroutine dcopy