Math.Sin Function Not Working for some values of the input argument

studentLwatch — Mon, 21 Feb 2011 05:51:37 GMT

Hi,

I'm using CodeWarrior v 5.9.0 and DSP board MC56F8037

I'm trying to calculate Sin(arg) and Cos(arg) (to get parameters for FFT analysis)

for (k = 1; k < transformLength; k++)

{

arg = 2*(float)bin*M_PI*(float)k / (float)transformLength;

sinPart = sinPart+(inputData[k] * sign * sin(arg);

cosPart = cosPart + (inputData[k] * cos(arg));

}

The problem is sin(arg) works fine for many values of arg, but for some values of arg it gives TOTALY different output values and destroys all the calculations furhter on.

Example

In CodeWarrior when i debug(having imported Math.h) i get

sin(11.584)=0.968

When i calculate on the calculator (as well as try to calculate in c sharp coded program) It gives

sin(11.584) = -0.828

This is such a huge difference...and it happens for random samples.

For other samples like sin(5.694)=-0.555 both in COdeWarrior and C Shapr the values are the SAME.

THIS has been really really driving me crazy.

Please, Could you look at this ... Is this a bug???

Re: Math.Sin Function Not Working for some values of the input argument

CrasyCat — Mon, 21 Feb 2011 15:57:31 GMT

Hello

I would recommend you to submit a service request to get support people looking at that.

Click here to submit a service request.

Make sure to attach a reproducible project and installed product information to the service request.

CrasyCat

topic Math.Sin Function Not Working for some values of the input argument in Classic/Legacy CodeWarrior

Math.Sin Function Not Working for some values of the input argument

Re: Math.Sin Function Not Working for some values of the input argument