# [R] Eq. Solution?

Yves Gauvreau cyg at sympatico.ca
Sat Sep 16 20:05:01 CEST 2000

```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

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