Stuart Allman wrote:
>
> Thanks for everyone's help.  I found a pretty easy way to find the log10.
> I'll just going to scale the numbers to between 0 and 1/2 (the spec has
> changed since my first post).  Then use 3.33*(sqrt(sqrt(x))-3  That should
> be just enough accuracy, considering that I am only dealing with four
> decimal places.
>
> This also works for numbers between 0 and 1 in case anyone is interested;  I
> didn't bother to test anything beyond that.  I hope this helps other people.
>


So, are you saying
log10(x) ~ 3.33*sqrt(sqrt(x)) - 3,  for  0 < x <= .5     ?

I created a little table over the range of values. This approximation does not
provide four decimal places of accuracy.

    x     log10(x)    approximation    error
---------------------------------------------
    .1      -1            -1.127       -12.7%
    .2      -.6990        -0.7731      -10.6%
    .3      -.5229        -0.5355       -2.4%
    .4      -.3979        -0.3517       11.6%
    .5      -.3010        -0.1998       33.6%

Did I miss something?

Scott