Hi, I have the following equation that I most solve for thau quite often to evaluate something else: thau = exp(ak/ak1 t thau), => ak, ak1, t > 0 I used Mathematica to solve it symbolically and it give, beside the usual warnings, a solution which involves a special function that R doesn't have "ProductLog". I used it in Mathematica to find numerical solutions but I always get imaginary solution. Thus I suppose the solution is unusable. The author say's that when ak/ak1 <= 0 there is always a real solution and when the ratio is > 0 there may be 1, 2 or no real solutions. So my question is how could I solve this "numerically" in R? Thanks. Yves Gauvreau -.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.- r-help mailing list -- Read http://www.ci.tuwien.ac.at/~hornik/R/R-FAQ.html Send "info", "help", or "[un]subscribe" (in the "body", not the subject !) To: r-help-request at stat.math.ethz.ch _._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._