Subject: seeking help with solving implicit equation
From: Robert Dodier
Date: Sat, 26 Jan 2008 09:37:08 -0700
On 1/25/08, dlakelan <dlakelan at street-artists.org> wrote:
> here's an example of how to solve for f after plugging in Re=17000,
> e=.01, and D=.25. Note than in maxima "log" means natural log. However
> this equation is defined in terms of log base 10 I believe.
As it happens there is an add-on package for log10.
See the comment header of share/contrib/log10.mac for more info.
(%i1) display2d : false;
(%o1) false
(%i2) load (log10);
(%o2) "/usr/local/share/maxima/5.14.0cvs/share/contrib/log10.mac"
(%i3) eqn : 1/sqrt(f) + 2*log10(e/D/3.7 + 2.51/Re/sqrt(f));
(%o3) 2*log10(.2702702702702702*e/D+2.51/(sqrt(f)*Re))+1/sqrt(f)
(%i4) find_root (eqn, f, 1e-7, 1), e=.01, D=.25, Re=17000;
(%o4) .06617475278925225
HTH
Robert Dodier