[Kst] [Kst-plot/kst] 944119: Change differentiation algorithm so that it is eas...

[Nicolas Brisset]

> I assume inputScalar->value() could take any value, also 0,
> in this case kst crashes.
This is checked for a few lines above:

  if (inputScalar->value() == 0) {
    _errorString = "Error:  Input Scalar Step must be not be 0.";
    return false;
  }

But I must admit I haven't tried it to see what really happens...

Nicolas