Andrew R

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5 years, 4 months ago.

Calculation always evaluates to 0

Hello,

in the code snippet below, both gain_range and gain_SYSTEM are declared as float earlier in the program.

However, both gain_calc and volume_display always evaluate to 0. I can only get a non zero (and correct answer) if I remove the division in the gain_calc formula.

Any ideas about what I am doing wrong?

Thanks

AndrewR

  gain_range = (rint(gain_SYSTEM)) - vol_min;
    gain_calc =  ((lr_volume - vol_min)/gain_range)*16;  //((lr_volume - vol_min)/gain_range)*16;
    volume_display = rint(gain_calc); //normalized count out of 16
    printf("gain_calc = %f gain range  %d lr_volume %d vol_disp %d \n\r",gain_calc, gain_range, lr_volume, volume_display);
    vol_disp();

1 Answer

Zoltan Hudak
5 years, 4 months ago.

Hellow Andrew,

  • Is gain_calc declared as float?
  • Try to first multiply and then divide when calculating gain_calc : 

gain_calc =  ((lr_volume - vol_min)*16.0f)/gain_range;

Zoltan,

thank you for your prompt reply - much appreciated.

Indeed, the problem has turned out to be me mixing typecasts - specifically double and float. When I declared gain_range as double, the problem was resolved.

posted by Andrew R 02 Dec 2018