• State Resolved
  • Locked Locked
  • Replies 1 reply
  • Subscribers 54 subscribers
  • Views 1978 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

Behaviour of power function

Amtech
Genius 4585 points
Other Parts Discussed in Thread: TMS320F28377D

Hi All,

I am using TMS320F28377D for my inverter application. In my software i have to use power function. Which is defined under math.h as "double pow(double x, double y);".

I have noticed strange behaviour of pow function. For Example,

pow(2,14) returenes = 16384. (OK that is fine)

But, pow(2,15) returenes = 32767.98 instead of 32768.

I can not accept this minor change please suggest any solution. I have captured image as i observed and that is attached herewith.

Thanks and Regards,

Maulik

 


  • 0
    Guru 92251 points

    Amtech said:
    I can not accept this minor change please suggest any solution. I have captured image as i observed and that is attached herewith.

    I haven't investigated the accuracy of the floating point pow() function, but notice that your code raises 2 to an integer power.

    In which case, the example could instead use a shift. e.g.:

        temp_bit = 1 << j;
    temp_bit = ~temp_bit;

    Is an integer shift suitable for your program?