Hi Tima, forget my guess! I have not recognized, that X is also known. Manu > Hi Tima, > > > Does somebody knows how to resolve this equation with Scilab: > > > > *X=C*dT/dt + R(T1-T2);* > > X = (C * (T1 - T2) / (t1 - t2)) + R(T1 - T2) > (with index 1 > 2)