segmetation fault

Sorry, one more thing.  Sometimes if crashes with Abort trap and sometimes it crashes with Segmentation fault.  Help!

 Thanks!

Elizabeth Lawson <lizzylaws at yahoo.com> wrote:
 I fixed the problem that I was having with the segmentation error and can load it with dyn.load.

I have one more problem now that I don't understand. I am using the .C in a for loop
for( i in 1:ncol(L.D)){
new[,i]<-.C("mycode",as.double(L.D[,i]))
}

It crashes at different places each time I try to run it. So I tried
i<-1
then running
new[,i]<-.C("mycode",as.double(L.D[,i]))
repeatedly.

It works for 3-6 times then will crash with the error
abort trap

What does this mean?
Why does it work sometimes and not others?

Any suggestions?

Thanks,

Elizabeth Lawson
"Kort, Eric" wrote:

Elizabeth Lawson Wrote:

Hey,

I don;t know if anyone has come across this error before...

More times than I care to remember.

I am running R on the terminal of my MAC OS X 10.3.4 and I have

written

C code and compiled it using
R CMD SHLIB mycode.c
There were no problems in compiling so I now have mycode.o and

mycode.so.

A segmentation fault occurs when you try to access memory you didn't
allocate for your use (see below). In other words, you are trying to
use memory outside the segment allocated to your program (which, if
allowed, could result in corrupting memory being used by other
programs--which brings back unhappy memories of days gone by when an
error in one program could crash the whole system). So these kinds of
problems will not show up at compile time...only when you actually run
the program.

I used dyn.load("mycode.so") and again, no problems. But when I try

to

use the code .C("mycode",x) I get the error Segmentation fault and R

shuts

down. Any ideas as to where my problem could be?

When I run into a segmentation fault, it is usually because I am trying
to access an element of an array that is beyond what I have allocated,
as in...

int main()
{
int *a;
a = (int*) malloc(3*sizeof(int));
printf("Fasten your seatbelts...\n");
a[4000] = 12;
return(0);
}

One less obvious way this can happen is forgetting to initialize your
arrays to the proper length before passing a reference to them to your C
function.

If you still are having trouble, you could post a small snippet of code
that recreates the error for us to examine.

HTH,
Eric


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