Re: changing variable in an equation

*To*: mathgroup at smc.vnet.net*Subject*: [mg116410] Re: changing variable in an equation*From*: Albert Retey <awnl at gmx-topmail.de>*Date*: Sun, 13 Feb 2011 05:51:16 -0500 (EST)*References*: <201102110917.EAA07980@smc.vnet.net> <201102121020.FAA20150@smc.vnet.net> <ij83dr$n1$1@smc.vnet.net>

Hi, > Those that have responded have requested further information. I hope this > will help. > ... > What I tried to do was to just plot his solution which is V(t)= Vsubnl + (V0 > - Vsubnl)times e to the -gsubL * t divided by c. What I did was make up > different equations such as vt1 = -67+(0-(-67))*e^-19t/c and substitute > values for t. And then make another equation with a different V0 and do the > same thing. Then finally combine them using Plot{{vt1,vt2 and so on}, > {t,0,5}]. > > These results mimic his plots so I am on the right track. It's just that my > way takes an enormous amount of time. I know that there must be a better > way to do this with Mathematica. That's the whole point of my request for > help. I'm not sure whether I got what you want and don't have the book to check, but I think the following should be a starting point to achieve what you probably want: sol = VsubnL + (V0 - VsubnL)*E^(-gsubL*t/c) parameters = {c -> 10, gsubL -> 19, VsubnL -> -67} Plot[Evaluate[Table[sol /. parameters, {V0, 0, 100, 20}]], {t, 0, 5}, Frame -> True, Axes -> False, PlotRange -> All, ImageSize -> 500] hth, albert

**References**:**changing variable in an equation***From:*"J and B" <noslowski@comcast.net>

**Re: changing variable in an equation***From:*DrMajorBob <btreat1@austin.rr.com>