asin function on LPC1768

Hello

I am using LPC1768 for a motor control application. The motor will be 
controlled with a series of pulses each of 2us wide.

I use a asin function to calculate the time between two pulses. (The 
motor moves clock and anti-clock wise, hence a sin function is 
considered)

when asin function is called, the code tends to break. ie it gets stuck 
at hardware handler routine.

I believe the issue is with the use of asin function, although i am not 
sure about it. I am using inbuilt asin in math.h

Can anyone kindly suggest me how to use a asin function on LPC1768. If 
anyone can provide me a small code for how to use it on LPC1768 would be 
of great help.

I have tried the code on rowley crossworks and on Keil. Both seem to 
give the same error. But in simulator asin function is working fine.

Kindly suggest.

Regards

Prakash