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RE: Solving a DE using Mathematica

• To: mathgroup at smc.vnet.net
• Subject: [mg90454] RE: [mg90424] Solving a DE using Mathematica
• From: "Tony Harker" <a.harker at ucl.ac.uk>
• Date: Thu, 10 Jul 2008 06:32:55 -0400 (EDT)

 You are setting off at a disadvantage by using a Real (0.016) in the
equation. If you replace this with 16/1000 and hit the result of the
back-substitution with FullSimplify you'll get confirmation of your solution
(Mathematica 6.0.3.0).

  Tony Harker 

]-> -----Original Message-----
]-> From: Greg [mailto:starwar636 at aol.com] 
]-> Sent: 09 July 2008 09:52
]-> To: mathgroup at smc.vnet.net
]-> Subject: [mg90424] Solving a DE using Mathematica
]-> 
]-> I'm having problems solving this problem although it should 
]-> appear pretty straightfoward:
]-> 
]-> (-l^2 - m^2 + n^2/(r + 0.016 z)^2) Z[z] + Z''[z] == 0
]-> 
]-> I am solving for Z[z].  These are the lines I use:
]-> 
]-> DSolve[Above Equation, Z[z], z]
]-> 
]-> I get an odd solution so I do a solution check plugging 
]-> back in Z[z] and Z''[z] yet I don't get 0.  In the above, 
]-> l,m,n,r are all constants.
]-> 
]->