[giac] fix circle intersection

c1:=circle(0,5);c2:=circle(4,10);C:=inter(c1,c2); git-svn-id: https://dev.geogebra.org/svn/trunk/geogebra/giac@70048 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e
geogebra · Oct 30, 2022 · dae6aff · dae6aff
1 parent 2c39c23
commit dae6aff
Showing 1 changed file with 4 additions and 1 deletion.
diff --git a/src/giac/cpp/plot.cc b/src/giac/cpp/plot.cc
@@ -9719,7 +9719,10 @@ namespace giac {
     // delta=ra^2-rb^2+AB^2
     gen delta=rayon_a2-rayon_b2+ab2;
     gen ab4=centre_a+delta/2/ab2*ab;
-    gen d_perp(sqrt(4*ab2*rayon_a2-pow(delta,2),contextptr)/2/ab2);
+    gen D=4*ab2*rayon_a2-pow(delta,2);
+    if (is_strictly_greater(0,D,contextptr))
+      return vecteur(0);
+    gen d_perp(sqrt(D,contextptr)/2/ab2);
     if (a2d){ // circle inter circle = 2 points (or 1)
       gen ab_perp(im(ab,contextptr)-cst_i*re(ab,contextptr));
       return makevecteur(symb_pnt(ratnormal(ab4+d_perp*ab_perp,contextptr),default_color(contextptr),contextptr),symb_pnt(ratnormal(ab4-d_perp*ab_perp,contextptr),default_color(contextptr),contextptr));