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Re: Why these graphs differ?


Vladimir Bondarenko wrote:
> 
> These solutions, naturally, coincide.
> 
>          DSolve[{y'[z] == z, y[0] == 1}, y[z], z][[1, 1, 2]]
> Evaluate[DSolve[{y'[z] == z, y[0] == 1}, y[z], z][[1, 1, 2]]]
> 
> (2 + z^2)/2
> (2 + z^2)/2
> 
> But, surprisingly, the corresponding graphs are not identical:
> 
> Plot[         DSolve[{y'[z] == z, y[0] == 1}, y[z], z][[1, 1, 2]],  {z, 0, 1}]
> Plot[Evaluate[DSolve[{y'[z] == z, y[0] == 1}, y[z], z][[1, 1, 2]]], {z, 0, 1}]
> 
> Is it a feature or a problem?

The Part[expr,1,1,2] is z for expr:> DSolve[{y'[z] == z, y[0] == 1},
y[z], z]

and the Part[expr,1,1,2] is (2+z^2)/2 for expr:>  {{y[z] -> (2 +
z^2)/2}}

so there is no wonder, that the results are differnt. Different
expressions
may have also different parts.

Regards
  Jens


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