Infinity found with unmap function of rsParameterMapper stuff

[elanhickler]

p = new jura::ModulatableParameter("spike", -1, 1, 0, jura::Parameter::LINEAR);
addObservedParameter(p);
p->setValueChangeCallback([this](double v) { oscillator.setBendSymmetrical(v); });
p->setMapper(new jura::rsParameterMapperTanh(-1, 1, 5));

x becomes infinity if y is over 1

tanH code

  double map(double x) const override
  { 
    x = 2*x - 1;           // 0..1 to -1..+1
    return a * tanh(b*x);  // -max..max
      // maybe generalize to y = a * tanh(b*(x+c)) + d for unsymmetric ranges, etc. 
  } 

  double unmap(double y) const override
  { 
    y = atanh(y/a) / b;    // -1..+1
    return 0.5 * (y+1);    //  0..1
  }

if tanH shape is 5, and we set parameter value to 1 (with an input box value entry! not with mouse) we get infinities, something to do with the unmapped normalized value going over 1 (it was like 1.0000084 or something). Please fix, I was very much enjoying the fine control of having a shape of 5!

temporary fix

i dunno what this is but...

[RobinSchmidt]

hmm...actually, infinity is the proper value of atanh(1):

https://www.desmos.com/calculator/9jrf3hkipt

(and above 1, it's actually not even defined). so, maybe we need indeed to hack around with clipping or whatever. but the error doesn't seem to have to with infinity per se but with my root-finding algorithm not converging (which could be because the function is so flat in that area). i could try a more robust (but typically slower) root-finding algorithm such as bisection (instead of false position) ....or finally implement brent's method (i want to have that algorithm in the library at some point anyway). would be best, if i could try this in the debugger myself. what would i have to do?

[elanhickler]

RhythmAndPitchModule.cpp

set to 1 instead of .99999

double click on the widget in the UI and enter 1.

you will get an infinite hang because I calculate knob arc based on normalized value which will be infinite, so you'll have to put a breakpoint where I have circled or you can't debug.

[elanhickler]

I'm not on your latest build so there will be lots of errors. Use build from September 27 2018" fixed mac build issues"

[RobinSchmidt]

ok, i can reproduce it now in my DebugAudioModule. hmmm....this is some numerical precision issue...i have to experiment with my convergence criterion in the root finder...maybe i'm dividing by a difference of numbers which gives zero....need to investigate...i think i will have to create a unit test for my root-finder and throw some "evil" functions at it...