amzoti
Posts:
1,108
Registered:
3/6/07


Re: Result to DEQ with WA versus StepbyStep Yields
Posted:
Feb 7, 2014 1:24 AM


On Saturday, February 1, 2014 8:44:33 PM UTC8, Bob Hanlon wrote: > The stepbystep solution provides the result for t >= 0 > > > > > > sol = ((WolframAlpha[ > > "v''+10 v'+125 v=250 unitstep(t),v(0)=0,v'(0)=25", > > {{"DifferentialEquationSolution", 1}, "Output"}] // > > ReleaseHold)[[1]]) // ToRules > > > > > > {v[t] > ((5/2)*Sin[10*t])/E^(5*t) + > > ((((5/2))*Sin[10*t])/E^(5*t) + > > ((1/2)*(4*E^(5*t)  4*Cos[10*t] + 3*Sin[10*t]))/ > > E^(5*t))*UnitStep[t]} > > > > > > > > Simplify[sol, t >= 0] > > > > > > {v[t] > 2  (2*Cos[10*t])/E^(5*t) + > > ((3/2)*Sin[10*t])/E^(5*t)} > > > > > > > > Bob Hanlon > > > > > > On Sat, Feb 1, 2014 at 12:54 AM, amzoti <amzoti@gmail.com> wrote: > > > > > When you solve this DEW using WA, you get a result. > > > > > > However, when you click stepbystep, the result is different. > > > > > > Is this a bug? > > > > > > v'' + 10 v' + 125 v = 250 unitstep(t), v(0) = 0, v'(0) = 25 > > > > > > Thanks > > > > > >
Thanks all!
Bob Hanlon: I see that you reply to many posting with excellent feedback.
I have always wondered (as your posts are different than many in a very good way), how did you learn Mathematica so well?
What approach and/or references did you use?
Regards A

