18 lines
512 B
Fortran
18 lines
512 B
Fortran
FUNCTION YINT(XL,YL,XL0)
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C
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C Quadratic interpolation routine
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C
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C Input: XL - array of x
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C YL - array of f(x)
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C XL0 - the point x(0) to which one interpolates
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C
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INCLUDE 'PARAMS.FOR'
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DIMENSION XL(3),YL(3)
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A0=(XL(2)-XL(1))*(XL(3)-XL(2))*(XL(3)-XL(1))
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A1=(XL0-XL(2))*(XL0-XL(3))*(XL(3)-XL(2))
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A2=(XL0-XL(1))*(XL(3)-XL0)*(XL(3)-XL(1))
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A3=(XL0-XL(1))*(XL0-XL(2))*(XL(2)-XL(1))
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YINT=(YL(1)*A1+YL(2)*A2+YL(3)*A3)/A0
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RETURN
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END
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