DSolve

*To*: mathgroup at smc.vnet.net*Subject*: [mg18738] DSolve*From*: shamsundar at uh.edu (N. Shamsundar)*Date*: Sat, 17 Jul 1999 02:36:51 -0400*Organization*: University of Houston*Sender*: owner-wri-mathgroup at wolfram.com

Here is a pair of differential equations that Version 3 could not solve (actually, it was still trying after 15 minutes on a 400 MHz PII!) w:=Exp[-a x]; DSolve[{u'[x]==-u[x]+v[x]+w (1-a)+Cos[Pi x]-(1+Pi) Sin[Pi x], v''''[x]==u[x]+v[x]+(Pi^4-1) Sin[Pi x]-Cos[Pi x]-w, u[0]==2, v[0]==0,v''[0]==0,v[1]==0,v''[1]==0}, {u[x],v[x]},x] These are linear equations with constant coefficients, and the exact solution is u=w+cos(Pi x), v=sin(Pi x) I would appreciate someone running this calculation in Version 4. N. Shamsundar University of Houston