CAS and small numbers

[Nigel (UK)]

(04-23-2014 07:14 AM)parisse Wrote:  I would recommend using symbols for physical constants, e.g. h for the Planck constant, then at the end of the computation replace h and other constants by their numerical value, for example
subst(expression,[h,q],[6.626e-34,1.6e-19])
or with units:
mksa(subst(h/m*q,[h,m,q],[_h_,_me_,_qe_]))

Thank you for these suggestions; the first works, and I shall use it.

The problem with your second suggestion is that mksa(_h_) (for example) gives zero, but with the correct units! If I'm solving for something that is small (energies in joules, masses in kilograms, charges in coulombs) I'll just get zero as my answer. Is this behaviour intended?

Nigel (UK)