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2608
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1 subroutine dcopy(n,dx,incx,dy,incy) |
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2 c |
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3 c copies a vector, x, to a vector, y. |
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4 c uses unrolled loops for increments equal to one. |
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5 c jack dongarra, linpack, 3/11/78. |
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6 c modified 12/3/93, array(1) declarations changed to array(*) |
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7 c |
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8 double precision dx(*),dy(*) |
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9 integer i,incx,incy,ix,iy,m,mp1,n |
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10 c |
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11 if(n.le.0)return |
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12 if(incx.eq.1.and.incy.eq.1)go to 20 |
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13 c |
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14 c code for unequal increments or equal increments |
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15 c not equal to 1 |
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16 c |
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17 ix = 1 |
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18 iy = 1 |
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19 if(incx.lt.0)ix = (-n+1)*incx + 1 |
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20 if(incy.lt.0)iy = (-n+1)*incy + 1 |
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21 do 10 i = 1,n |
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22 dy(iy) = dx(ix) |
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23 ix = ix + incx |
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24 iy = iy + incy |
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25 10 continue |
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26 return |
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27 c |
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28 c code for both increments equal to 1 |
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29 c |
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30 c |
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31 c clean-up loop |
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32 c |
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33 20 m = mod(n,7) |
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34 if( m .eq. 0 ) go to 40 |
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35 do 30 i = 1,m |
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36 dy(i) = dx(i) |
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37 30 continue |
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38 if( n .lt. 7 ) return |
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39 40 mp1 = m + 1 |
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40 do 50 i = mp1,n,7 |
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41 dy(i) = dx(i) |
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42 dy(i + 1) = dx(i + 1) |
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43 dy(i + 2) = dx(i + 2) |
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44 dy(i + 3) = dx(i + 3) |
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45 dy(i + 4) = dx(i + 4) |
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46 dy(i + 5) = dx(i + 5) |
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47 dy(i + 6) = dx(i + 6) |
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48 50 continue |
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49 return |
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50 end |
