Series #1: M value

Hi Alan, long time no see. Hope you are well!

We could also use the "root" function to do the job - its available in Prime Express, too.

Of course we would have define S.inf manually as in Express we have no symbolics.

As with "root" we can only check for equality within tolerance, I guess its also necessary to check the function value of the solution given as it may be that we have to use the next largest instead.