Re: DSOLVE in 5.01 ??
- To: mathgroup at smc.vnet.net
- Subject: [mg47642] Re: DSOLVE in 5.01 ??
- From: turbo cyx <turbocyx at gmx.net>
- Date: Tue, 20 Apr 2004 03:18:46 -0400 (EDT)
- References: <c5j82s$r3h$1@smc.vnet.net> <c5oaui$1fl$1@smc.vnet.net> <c5qj6n$fvp$1@smc.vnet.net> <c5ten8$hum$1@smc.vnet.net>
- Sender: owner-wri-mathgroup at wolfram.com
So its since 4.1, does this change anything?? and no, I am not steve_H Cu Cyx On Sun, 18 Apr 2004 08:36:56 +0000 (UTC), "Peter Pein" <petsie at arcor.de> wrote: >"turbo cyx" <turbocyx at gmx.net> schrieb im Newsbeitrag >news:c5qj6n$fvp$1 at smc.vnet.net... >> Why should I bother with this?? I am not willing to use workarounds >> for Wolfram bugs (I am coauthor of a widely used courseware in >> austria. Now I have to write this workaround for all the Lessons wich >> use DSolve and boundary conditions, in a few month when 6.0 finally is >> available I can undo this again ....) >> Mathematica 4.2 (and all previous version) has been able to solve this >system, >> so I think 5.01 should be also (BTW: 6.0 Alpha can solve this system >> again) >> Wolfram where is a bugfix >> Cyx >> >Mathematica 4.0 must have been published after vers. 4.2: > >In[1]:= >$Version >dgl1 = m*g - c*v[t]^2 == m*Derivative[1][v][t]; >dgl2 = Derivative[1][s][t] == -v[t]; >DSolve[{dgl1, dgl2, s[0] == h0, v[0] == 0}, {s[t], v[t]}, t] >Out[1]= >4.0 for Microsoft Windows (July 16, 1999) >From In[1]:= >Solve::incnst: > Inconsistent or redundant transcendental equation. After > Sqrt[g] Sqrt[m] C[2] 2 > reduction, the bad equation is 1 - Cosh[--------------------] > Sqrt[c] > == 0. >From In[1]:= >Solve::incnst: > Inconsistent or redundant transcendental equation. After > Sqrt[g] Sqrt[m] C[2] 2 > reduction, the bad equation is 1 - Cosh[--------------------] > Sqrt[c] > == 0. >From In[1]:= >Solve::tdep: The equations appear to involve the variables to be > solved for in an essentially non-algebraic way. >From In[1]:= >DSolve::dsing: > Unable to fit initial/boundary conditions {s[0] == h0, v[0] == 0} > . >Out[4]= >{} >In[5]:= >DSolve[{dgl1,v[0]==0},v[t],t] >Out[5]= > Sqrt[c] Sqrt[g] t > Sqrt[g] Sqrt[m] Tanh[-----------------] > Sqrt[m] >{{v[t] -> ---------------------------------------}} > Sqrt[c] >In[6]:= >Integrate[-v[t]/.%[[1]],{t,0,z}]+h0 >Out[6]= > Sqrt[c] Sqrt[g] z > m Log[Cosh[-----------------]] > Sqrt[m] >h0 - ------------------------------ > c > >please check your statements _before_ posting (b.t.w. are you known as >steve_H in sci.math.symbolic?). > >Thanks