DSolve&NDSOLve with 3.0.1, w95

*To*: mathgroup at smc.vnet.net*Subject*: [mg12858] DSolve&NDSOLve with 3.0.1, w95*From*: mhicks <marlyn.hicks at Cubic.COM>*Date*: Wed, 17 Jun 1998 00:28:01 -0400*Organization*: xcubic*Sender*: owner-wri-mathgroup at wolfram.com

I need some advice! Both the instructions below return solutions with math 2.2.1. 3.0.1 returns excuses by the page full. Am I missing something, or has mathematica lost something between 2.2.1 and 3.0.1? I suspect the fault is mine since I have not noted discussion of this problem here or otherwise. I would appreciate any help anyone can offer. meanwhile, I will carefully retain 2.2.1..... gv=1;gp=.02;gr=.0001;ar=1;ai=.99; DSolve[{ac'''[t]+gv ac''[t]+gp ac'[t]+gr ac[t]== (ai-ar) gr, ac[0]==0, ac'[0]==(ai-ar) gv, ac''[0]==(ai-ar) gp-gv ac'[0]}, ac[t], t] Clear[ai,ar,t,v];kv=1;ka=.2;kj=.0016; vt=NDSolve[{v''''[t]+kv v'''[t]+ka v''[t]+kj v'[t]== ka ar'[t]+kj ar[t], p''''[t]+kv p'''[t]+ka p''[t]== v'''[t]+kv ar'[t]+ka ar[t], ar'[t]==.1, v[0]==0, v'[0]==.9, v''[0]==.09+kv-.9 kv, v'''[0]==ar'[0] kv +ka ar[0]-v''[0] kv-v'[0] ka, ar''[0]==0, ar'[0]==.1, ar[0]==1, p'''[0]==.29, p''[0]==.9, p'[0] ==0, p[0]==0}, {v[t], p[t], ar[t]}, {t, 0, 1000}] -- ned!