Unable to sort symbolic variables in matlab

There is a an issue in one section of my code. Let I have this symbolic equation. When i use the coeffs function like this it gives me the right coefficients and variables.

eq=(10219275*P10_10)/2097152 - P10_9/10 - P9_10/10
[a,b]=coeffs(eq);
a =
[ -1/10, 10219275/2097152, -1/10]
b =
[ P10_9, P10_10, P9_10]

but i want it to return me the variables and its coefficients in this order. How can i go about this rearrangement.

b =
    [ P9_10, P10_9, P10_10]

Please help me.

Answer 1

[Star Strider]

You can tell coeffs the order in which you want the coefficients returned:

syms P10_9 P10_10 P9_10
eq=(10219275*P10_10)/2097152 - P10_9/10 - P9_10/10
[a,b]=coeffs(eq, [P9_10, P10_9, P10_10])

a =
[ -1/10, -1/10, 10219275/2097152]

b =
[ P9_10, P10_9, P10_10]

[Aftab Ahmed Khan]

Hahahahahaha Man. Your solution solved my question here but my problem here is a small piece of my actual problem in which i have 100 equations. So, i can't pass it like you suggested.

[Star Strider]

How do you want them sorted? I don’t see a pattern.

[Walter Roberson]

Sort order is first by the number after 'P' and before the '_', and secondarily by the number after the '_'

[Aftab Ahmed Khan]

Well, i have managed to do it in another way found on the internet. Thanks once again.

Answer 2

[Walter Roberson]

Use http://www.mathworks.com/matlabcentral/fileexchange/10959-sort-nat--natural-order-sort a "natural sort" on the output of symvar() to get the order you want to do the sorting in, and then pass the sorted result as the second parameter of coeffs