First of all thanks a lot for the hints.

Here it is an esxample, the equations are trigonometric, the solution has polynomials of high order:

solve({a3-b1*cos(beta)-a1*sin(alpha)-b2*sin(epsilon)-a2*cos(delta) = 0, a1*cos(alpha)-b3-b1*sin(beta)-b2*cos(epsilon)+a2*sin(delta) = 0}, {alpha, beta})

I found the error, my mistake sorry!!!

If it is not clear from the previous post these are the lines I wrote:

eq := [piecewise(p(t) < prec, p(t) = C1*exp(function), p(t) >= prec, p(t) = C1*exp(function))];


  params := [C1 = .2, prec = 100.];
 

sys := DynamicSystems[AlgEquation](eq, inputvariable = [function], outputvariable = [p(t)]);

 I understand now!!!