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Initial condition with DSolve in Mathematica 8 doesn't work

  • To: mathgroup at smc.vnet.net
  • Subject: [mg115984] Initial condition with DSolve in Mathematica 8 doesn't work
  • From: Bert RAM Aerts <bert.ram.aerts at gmail.com>
  • Date: Fri, 28 Jan 2011 06:14:21 -0500 (EST)

When I enter the following in Mathematica 8.0.0 Home Edition:
DSolve[{y'[x] + y[x] == a Sin[x], y[0] == 0}, y[x], x]
I get
DSolve::deqn: Equation or list of equations expected instead of True
in the first argument {y[x]+(y^\[Prime])[x]==a Sin[x],True}. >>

The initial condition becomes a "True"...

In Mathematica 7.0.1 Home Edition, this same input gives the expected
output:
{{y[x] -> -(1/2) a E^-x (-1 + E^x Cos[x] - E^x Sin[x])}}

What am I missing?


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