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Examples of errors detected by the V550…

Examples of errors detected by the V550 diagnostic

Apr 05 2021

V550. An odd precise comparison. It's probably better to use a comparison with defined precision: fabs(A - B) < Epsilon or fabs(A - B) > Epsilon.


CAMEL

V550 An odd precise comparison: x == 0. It's probably better to use a comparison with defined precision: fabs(A - B) '<' Epsilon. clock_dll sunalgo.cpp 155


void projillum(short* wtab, int xdots, int ydots, double dec)
{
  ....
  s = sin(-dtr(dec));
  x = -s * sin(th);
  y = cos(th);
  ....
  lon = (y == 0 && x == 0) ? 0.0 : rtd(atan2(y, x));
}

It's strange to expect 'x' and 'y' to exactly equal 0 after all these calculations.

Similar errors can be found in some other places:

  • V550 An odd precise comparison: y == 0. It's probably better to use a comparison with defined precision: fabs(A - B) '<' Epsilon. clock_dll sunalgo.cpp 155

ffdshow

V550 An odd precise comparison: x == 0. It's probably better to use a comparison with defined precision: fabs(A - B) < Epsilon. resample2.cpp 166


static void av_build_filter(....)
{
  ....
  x = M_PI * ((double)(i - center) -
              (double)ph / phase_count) * factor;
  if (x == 0) y = 1.0;
  else        y = sin(x) / x;
  ....
}

It's strange to expect 'x' to exactly equal 0 after all these calculations.


Windows Calculator

V550 An odd precise comparison: ratio == threshold. It's probably better to use a comparison with defined precision: fabs(A - B) < Epsilon. Calculator AspectRatioTrigger.cpp 80


void AspectRatioTrigger::UpdateIsActive(Size sourceSize)
{
  double numerator, denominator;
  ....
  bool isActive = false;
  if (denominator > 0)
  {
    double ratio = numerator / denominator;
    double threshold = abs(Threshold);

    isActive = ((ratio > threshold) || (ActiveIfEqual && (ratio == threshold)));
  }

  SetActive(isActive);
}

Similar errors can be found in some other places:

  • V550 An odd precise comparison. It's probably better to use a comparison with defined precision: fabs(A - B) < Epsilon. CalcManager UnitConverter.cpp 752
  • V550 An odd precise comparison: stod(roundedString) != 0.0. It's probably better to use a comparison with defined precision: fabs(A - B) > Epsilon. CalcManager UnitConverter.cpp 778
  • V550 An odd precise comparison. It's probably better to use a comparison with defined precision: fabs(A - B) < Epsilon. CalcManager UnitConverter.cpp 790
  • And 9 additional diagnostic messages.

ArduPod

V550 An odd precise comparison: value != - 1. It's probably better to use a comparison with defined precision: fabs(A - B) > Epsilon. AP_Utils.cpp 574


float AP_Utils::sr04_average(uint8_t trig, uint8_t echo,
  int unit, int samples, int time) {
  ....
  float average, pause, value;
  ....
  for(int i=0; i<samples; i++) {
    value = sr04(trig, echo, unit);
    if(value != -1) { // <=
      total += value;
      delay(pause);
    } else {
      i--;
    }
  }
  average = total/samples;
  ....
  return average;
}

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