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How to use Real in DSolve?

Posted 9 years ago

I am trying to solve a differential equation of the form:

r'[t]==Real[F d[t]]+C r[t]

When C is a constant, F is a complex constant, and r[t] and d[t] are complex functions. I want to solve for r[t] and d[t] (there is another equation of a similar form) The function DSolve doesn't work with this syntax, and the problem is the Real[F d[t]] since when I remove the Real, Mathematica solves it. Can anyone help? Thanks a lot!

POSTED BY: shaked rozen
2 Replies

If by Real you meant the real part of a complex number, Mathematica gives a symbolic solution this way:

DSolve[r'[t] == Re[F d[t]] + C r[t], r[t], t]
POSTED BY: Gianluca Gorni
Posted 9 years ago

Real[] is used within Mathematica to indicate that the argument is a real constant.

Re[] is used to extract the real part of a potentially complex value. Is that perhaps more what you are looking for?

C is a reserved name within Mathematica. In rare cases it is possible to use C without conflicts. Using lower case for user names is often safer.

If you could provide more details it might be easier to provide suggestions.

POSTED BY: Bill Simpson
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