Improving stop criteria of brent solver (related to #116 )

src/dichotomie.ts

@@ -517,7 +517,13 @@ export class Dichotomie extends Debug {
             tolAct = 1e-15 * Math.abs(b) + errorTol / 2;
             newStep = (c - b) / 2;
 
-            if (Math.abs(newStep) <= tolAct && Math.abs(fb) < 0.1) {
+            if (
+                Math.abs(newStep) <= tolAct
+                && (
+                    Math.abs(fb) < errorTol
+                    || Math.abs(fb / (Math.abs(fb) - Math.abs(fc))) < 1
+                )
+            ) {
                 return b; // Acceptable approx. is found
             }