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2608
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1 integer function idamax(n,dx,incx) |
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2 c |
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3 c finds the index of element having max. absolute value. |
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4 c jack dongarra, linpack, 3/11/78. |
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5 c modified 3/93 to return if incx .le. 0. |
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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(*),dmax |
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9 integer i,incx,ix,n |
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10 c |
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11 idamax = 0 |
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12 if( n.lt.1 .or. incx.le.0 ) return |
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13 idamax = 1 |
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14 if(n.eq.1)return |
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15 if(incx.eq.1)go to 20 |
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16 c |
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17 c code for increment not equal to 1 |
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18 c |
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19 ix = 1 |
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20 dmax = dabs(dx(1)) |
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21 ix = ix + incx |
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22 do 10 i = 2,n |
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23 if(dabs(dx(ix)).le.dmax) go to 5 |
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24 idamax = i |
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25 dmax = dabs(dx(ix)) |
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26 5 ix = ix + incx |
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27 10 continue |
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28 return |
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29 c |
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30 c code for increment equal to 1 |
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31 c |
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32 20 dmax = dabs(dx(1)) |
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33 do 30 i = 2,n |
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34 if(dabs(dx(i)).le.dmax) go to 30 |
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35 idamax = i |
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36 dmax = dabs(dx(i)) |
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37 30 continue |
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38 return |
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39 end |
