Floating point calculation problem

Mauro Fantina

Hello,

I have this code and I noticed a strange problem:

void test(float a,float b)
{
	Uint32 c = (a/b)-1;
	if(c) asm(" ESTOP0");

	// here c = 199998 ?????
}

void main()
{
	test(200E6,1E3);
}

c is equal to 199998 instead of 199999 why ??

0 Gautam Iyer over 11 years ago

Guru 192875 points

Hi Mauro,

Which controller are you using for this computation?

Also, if you check this link, where Vishal clearly mentions that :

The result is 178 which you will have to divide by 100 - which WILL NOT GIVE YOU 1.78 BUT 1.779999....

200E6/1E3 would give you 199999 and not 200000! Hence you get the result as 199998.

Regards,

Gautam

0 Mauro Fantina over 11 years ago in reply to Gautam Iyer

Genius 3800 points

Delfino dual with fast fpu library

C2000 microcontrollers forum