How to wrap a glibc mathematical function using LD_PRELOAD - c

Question

I am trying to wrap the GLIBC math functions including summation, division, multiplication, Cosine, log, and etc. I found a similar post here.
I have created a wrapper script for the log function in which prints something before calculation. Something like this for log function:
#include <dlfcn.h>
#include <stdio.h>
#include <math.h>
static double (*real_log)(double dbl);
double log(double dbl)
{
printf("value is %0.16f\n" , dbl);
real_log = dlsym(RTLD_NEXT, "log");
real_log(dbl);
}
And the test file is something like this:
#include <stdio.h>
#include <math.h>
int main () {
double var;
var = log(2.7);
printf("log is equal to %0.16f\n" , var);
return 0;
}
I have re-compiled the wrapper to create the shared library by this command: gcc -fPIC -shared -o libpreload.so wrapper.c -ldl.
I compiled test file: gcc -fno-builtin-log test.c -o test -lm.
Then I run my test script using: LD_PRELOAD=/path/to/libpreload.so ./test
The output now prints
value is 2.7000000000000002
log is equal to 0.0000000000000000
The log returns zero value while I expect to get the real calculation like this:
value is 2.7000000000000002
log is equal to 0.9932517730102834
I'm so beginner on C programming and also Glibc functionality.
I would appreciate any ideas.