Error in Java translation of trstlp

[rruusu]

On line 1078 of Cobyla.java, there is a deviation from the behavior of the original Fortran code:

                    if (mcon == m)
                    {
                        double acca = step + 0.1 * resmax;
                        double accb = step + 0.2 * resmax;
                        if (step >= acca || acca >= accb) break L_70;
                        step = Math.min(step, resmax);
                    }

This corresponds to the following Fortran code:

        if (mcon == m) then
            acca = step + 0.1_wp * resmax
            accb = step + 0.2_wp * resmax
            if (step >= acca .or. acca >= accb) go to 480
            step = min (step, resmax)
        end if

The break L_70 statement takes the Java code to line 1184:

                if (step == stpful) return true;

This is equivalent to a go to statement to the line just above the label 480 in the original Fortran. In this case, the condition step == stpful is always true, resulting in a premature exit from trstlp, causing it to return a step of size zero, while claiming to have taken a full step and thus multiple evaluations of sample points.

In order to match the effects of the go to 480 statement in the Fortran code, the break L_70 statement should instead be continue L_60.