Dear R-list members,

I am calculating the linear extrapolation for a data set, using the function
found in Hmisc.

x=c(0.0265,-0.0003,0.0142,0.0263,0.0634,0.1145,0.2504)
y=c(58,107,152,239,362,512,724)
x1=0.0393216
approxExtrap(x,y,x1, method="linear")
approx(x,y,x1)

#to see what is happening:
plot(x, y, typ="o")
abline(v=x1, col=8)


Which gives x=0.03 and y=163, instead of the expectable which would be close
to y=300.
Any ideia why this is happening or how to sort this out?

Thank you vey much in advance,
Best wishes,
Marta

-- 
LNEG_VS_Poli_CMYK_300dpi

Laboratório Nacional de Energia e Geologia, I.P.

Estrada da Portela, Zambujal - Alfragide
Apartado 7586, 2720-866 Amadora
www.lneg.pt

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