topic Re: Unable to evaluate in Mathcad

Unable to evaluate

SS_9781956 — Mon, 04 Nov 2024 11:59:57 GMT

I have run into similar problem again where I am not able to evaluate the value stating it cannot assign value greater than 10^307 what is missing in here?

Re: Unable to evaluate

StuartBruff — Mon, 04 Nov 2024 12:23:34 GMT

Your exponential terms ... they're of the form e^-a*t+b, where a and b are large numbers. The -a isn't so bad, but as e^a+b = e^a·e^b, that e^b is smashing it out of the 64-bit park.

Stuart

Re: Unable to evaluate

SS_9781956 — Mon, 04 Nov 2024 17:34:57 GMT

So there is no possible way I can evaluate those?

Re: Unable to evaluate

Werner_E — Mon, 04 Nov 2024 19:31:51 GMT

You could use symbolic evaluation

Re: Unable to evaluate

Werner_E — Mon, 04 Nov 2024 19:58:57 GMT

Apart from my suggestion to use symbolic evaluation to get a numeric result I played around because I hoped that Prime would be able to simplify the symbolic expression so that it could be evaluated numerically as well.

What I found instead is what I would call a severe bug!

Using "simplify" changes the error message when trying to evaluate numerically (now "m" is said to be unknown/not defined) but also the numeric values in symbolic evaluations!!!

Without 'simplify'

now with 'simplify' added

EDIT: Further investigation showed that the bug has to do with the symbolics being forced to float mode by using floating point numbers.

When we change the definition of R.E from 0.01 to 1/100 and replace the two 0.2 in the definition Y.i(s) tp 1/5, the bug does not show when simplify is used (but numeric evaluation still would fail).

Nonetheless a severe bug. Someone should report it to R&D

Re: Unable to evaluate

ttokoro — Tue, 05 Nov 2024 00:49:25 GMT

Re: Unable to evaluate

Werner_E — Tue, 05 Nov 2024 02:34:20 GMT

Yes, zooming in may bring up surprising details ...