34 lines
777 B
Fortran
34 lines
777 B
Fortran
FUNCTION plgndr(l,m,x)
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INTEGER l,m
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REAL plgndr,x
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INTEGER i,ll
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REAL fact,pll,pmm,pmmp1,somx2
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if(m.lt.0.or.m.gt.l.or.abs(x).gt.1.)pause
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*'bad arguments in plgndr'
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pmm=1.
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if(m.gt.0) then
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somx2=sqrt((1.-x)*(1.+x))
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fact=1.
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do 11 i=1,m
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pmm=-pmm*fact*somx2
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fact=fact+2.
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11 continue
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endif
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if(l.eq.m) then
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plgndr=pmm
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else
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pmmp1=x*(2*m+1)*pmm
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if(l.eq.m+1) then
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plgndr=pmmp1
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else
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do 12 ll=m+2,l
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pll=(x*(2*ll-1)*pmmp1-(ll+m-1)*pmm)/(ll-m)
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pmm=pmmp1
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pmmp1=pll
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12 continue
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plgndr=pll
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endif
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endif
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return
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END
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