Does anyone know how -log(x) can equal 743 but -log(x+0)=Inf? That's what the following stream of calculations suggest:
Browse[2]> -log ( 1e-323+yMat2 - yMat1 * logitShape(matrix(parsList$Xs, nrow = numXs, ncol=numOfCurves), matrix(means, nrow = numXs, ncol=numOfCurves, byrow=TRUE), matrix(sigmas, nrow = numXs, ncol=numOfCurves, byrow=TRUE)) )[5,9] [1] Inf Yet: Browse[2]> logitShape(matrix(parsList$Xs, nrow = numXs, ncol=numOfCurves), matrix(means, nrow = numXs, ncol=numOfCurves, byrow=TRUE), matrix(sigmas, nrow = numXs, ncol=numOfCurves, byrow=TRUE))[5,9] [1] 1 So, the logitShape component equals 1. Browse[2]> yMat1[5,9] [1] 1 So yMat1[5,9]*logitShape()[5,9]=1 Browse[2]> yMat2[5,9] [1] 1 So, yMat2[5,9]-yMat1[5,9]*logitShape()[5,9]=0 Browse[2]> -log ( 1e-323) [1] 743.7469 So, -log( 1e-323)=743 while -log( 1e-323+0)=Inf ? Any idea of a neat way to get around this? Even if I put in 1e-50 I still get Inf. I deliberately included 1e-323 to insure the function didn't go to infinity. Peter ______________________________________________ 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
