There seems to be a problem with the TI-89 and TI-92+ software. Try: deSolve(y'=invsin(x+y),x,y) (invsin is the inverse sine function) I get with both calculators some thing like: ____________ = x+@1 invsin(x+y+1) Similar results with other transcendental functions but not all. Has there been any other problems like this been observed. G. Wardall wardallg@uwgb.edu