Question about mcc_rma_implicit_sinh_onevar.hpp

[GaglianoLuca]

What does it mean this part of the code? Could not be simplified like " dp0_depv = 0.5 *p0_min;" in the second part?

if (p0_helper > p0_min){
dp0_depv = 0.5 * (dp0_depv_helper + dp0_depv_helper - p0_min);
} else {
dp0_depv = 0.5 * (dp0_depv_helper + p0_min - dp0_depv_helper);
}

[larsblatny]

Hi @GaglianoLuca, thanks a lot for your question.

I believe you are right, I think it was originally written like this for symmetry.

The point of this part of the code is essentially to improve the convergence of the Newton-Raphson scheme as we are dealing with a non-smooth hardening law p0 = max( , Ksinh(-xiepv + asinh(p00/K))).

Maybe the original author @vertobi would like to add to this explanation?

[vertobi]

Hi @GaglianoLuca, you're right that these two lines of the code can be simplified. We could update it to:

if (p0_helper > p0_min) {
dp0_depv = dp0_depv_helper - 0.5 * p0_min;
} else {
dp0_depv = 0.5 * p0_min;
}

Thanks for catching this. As @larsblatny mentioned, this section was likely to help ensure dp0_depv is updating correctly, but I just directly translated what I had written on paper to code without taking a second look to simplify it at the time.

[larsblatny]

Thanks a lot for clarifying, @vertobi !
In case you happen to have some notes or references to the math behind how this if-else-statement for dp0_depv helps the calculation, please feel free to share them here