Displaying 6 results from an estimated 6 matches for "mankoo".
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mangoo
2010 Jul 06
2
numerical derivative R help
I fit my CDF to sum of exponentials and now I want to take the numerical
derivative of this function to obtain probability density.I will really
appreciate your help reagrding the error messages I am getting which I don't
understand.
*
*
> fitterma <- function(xtime) {
a <- -0.09144115
b <- -0.01335756
c <- -2.368057
d <- -0.00600052
2010 Jun 23
1
Probabilities from survfit.coxph:
Hello:
In the example below (or for a censored data) using survfit.coxph, can
anyone point me to a link or a pdf as to how the probabilities appearing in
bold under "summary(pred$surv)" are calculated? Do these represent
acumulative probability distribution in time (not including censored time)?
Thanks very much,
parmee
*fit <- coxph(Surv(futime, fustat) ~ age, data = ovarian)*
2010 Apr 01
1
predicted time length differs from survfit.coxph:
Hello All,
Does anyone know why length(fit1$time) < length(fit2$n) in survfit.coxph
output? Why is the predicted time length is not the same as the number of
samples (n)?
I tried: example(survfit.coxph).
Thanks,
parmee
> fit2$n
[1] 241
> fit2$time
[1] 0 31 32 60 61 152 153 174 273 277 362
365 499 517 518 547
[17] 566 638 700 760 791
2010 Jul 06
0
Help needed with numericDeriv and optim functions
Hello All:
I have defined the following function (fitterma as a sum of exponentials)
that best fits my cumulative distribution. I am also attaching the "xtime"
values that I have. I want to try two things as indicated below and am
experiencing problems. Any help will be greatly appreciated.
Best, Parmee
-----------------------
*fitterma <- function(xtime) { *
*a <-
2009 Nov 30
0
normalized kernel question:
Hey!
Can anyone help me coding in R a normalized kernel matrix.
Basically, I want
K(x,y)/sqrt(*K*(*x, x*)*K*(*y, y*))
Anyone has a piece of code that you could share?
Many thanks,
Parmee
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2010 Feb 23
0
BUG with LSSVM in R:
Hello,
I have noticed a bug with LSSVM implementation in R. It could be a bug with
the LSSVM itself that causes this problem.
I thought I should post this message to see if anyone else is familiar with
this problem and explain why the result is different for odd and even number
of cases.
Once the hyperplane is found using LSSVM, the prediction results vary when
you predict odd or even number of