how can I use parameter instead of equation in dsolve

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frank 2012-4-27

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评论： Luan Trinh 2014-11-26

Hi

I want to solve an ordinary differential symbolic equation with dsolve. But I want to save my equation in a parameter and use this parameter in dsolve. My codes are coming below:

      clear all
      syms a x
      l=a*x;
      dsolve('Dx=l')

these codes don't work. What should I do?

Thanks a lot

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Answer 1

Kai Gehrs 2012-4-27

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Hi Frank,

you can try something like

clear all; syms a x; l=a*x; dsolve(['Dx= ' char(l)])

The point is that variables/parameters inside a string cannot be "evaluated". But as the example suggests you can use the command CHAR to convert a symbolic expression to a character string and use the brackets to concatenate strings appropriately.

Hope this helps and best regards,

-- Kai