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piscal/dataassim/math/numrec/f77_sources/chebev.for
T
2016-02-03 18:52:05 +00:00

19 lines
398 B
Fortran

FUNCTION chebev(a,b,c,m,x)
INTEGER m
REAL chebev,a,b,x,c(m)
INTEGER j
REAL d,dd,sv,y,y2
if ((x-a)*(x-b).gt.0.) pause 'x not in range in chebev'
d=0.
dd=0.
y=(2.*x-a-b)/(b-a)
y2=2.*y
do 11 j=m,2,-1
sv=d
d=y2*d-dd+c(j)
dd=sv
11 continue
chebev=y*d-dd+0.5*c(1)
return
END