> This is obtained from F =39540 with df1 = 1, df2 = 7025. > Suppose am interested in exact value such as >
If it were really necessary, you would have to move to multiple precision. The gmp R package doesn't seem to yet cover this, but FMLIB (TOMS814, DM Smith) is a multiple precision f90 library that does include the incomplete beta -- it allows one to say for F(1,7025)=39540, P=6.31E-2886 (evaluated using 200 sign. digit arithmetic). Results from R's pf() agree quite closely with the FMLIB results for less extreme values eg > print(pf(1500,1,7025,lower=FALSE), digits=20) [1] 1.3702710894887480597e-297 cf 1.37027108948832580215549799419452388134616261215463681945E-297 | David Duffy (MBBS PhD) ,-_|\ | email: [EMAIL PROTECTED] ph: INT+61+7+3362-0217 fax: -0101 / * | Epidemiology Unit, Queensland Institute of Medical Research \_,-._/ | 300 Herston Rd, Brisbane, Queensland 4029, Australia GPG 4D0B994A v ______________________________________________ R-help@stat.math.ethz.ch mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html