| Author |
Comment/Response |
yehuda
|
 02/03/13 04:03am
Well, the fact that you get an answer from Maple is not a guarantee to a good answer
Try adding a parameter to the ODE
sol = DSolve[y'[x] == Tan[x + y[x]] + a, y[x], x]
you get the result
Solve[y[x] - (-Log[(1 + a) Cos[x + y[x]] + Sin[x + y[x]]] + (1 + a +
a^2) (x + y[x]))/(2 + 2 a + a^2) == C[1], y[x]]
Now check the limit of the left hand side within the Solve command
Limit[sol[[1, 1]], a -> 0]
returning
1/2 (-x + Log[Cos[x + y[x]] + Sin[x + y[x]]] + y[x])
That is, Log[Cos[x+y[x]] may be undefined if Cos[x+y[x]] equals zero
What are the initial conditions ? say that for x==0 y[0] ==Pi/2, then what???
yehuda
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