how can I use parameter instead of equation in dsolve
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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
采纳的回答
Kai Gehrs
2012-4-27
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
更多回答（1 个）
Walter Roberson
2012-4-27
dsolve( subs(sym('Dx=l')) )
4 个评论
Andrei Bobrov
2012-4-27
Hi Walter!
This is for MATLAB R2012a only?
Walter Roberson
2012-4-27
Shouldn't be. It is just using a straight-forwards subs().
frank
2012-4-28
Luan Trinh
2014-11-26
Hi everyone,
I want to know how to solve some ODEs like this: clear all; syms a x; l=a*x; dsolve(['D2x*' char(l)+ 'Dx*x' == 0])
Could you help me?
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