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# I would like to get the b value in Matalb.

Asked by Redwood on 16 May 2013

Dear Matlab experts,

I would like to get the b value in Matlab, but I got nothing in Matlab. I attached my coding below. Please let me know how to get the b value.

```syms b G G1 M1 M2 M3 P1 P2 P3
b  = 0:.0001:10;
Out=solve(' G1 == G*(P1*exp(-b*M1/P1)/( P1*exp(-b*M1/P1)+ P2*exp(-b*M2/P2) + P3*exp(-b*M3/P3)))', b)
G = [7340, 7194];
G1 = [4516.881,  5002.953];
M1 = [5222.328, 6009.419];
M2 = [3264.034, 2632.621];
M3 = [1264.034, 1632.621];
P1 = [3000, 3025];
P2 = [10000, 10051];
P3 = [5000, 5051];
Out=subs(Out)
```

Thank you very much in advance.

Sincerely,

Redwood

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Answer by Walter Roberson on 16 May 2013

Use

` syms b`

instead of assigning a numeric value to b.

Answer by Redwood on 16 May 2013

Dear Walter,

Thank you very much for your help.

But I did not get anything in Matlab.

Sincerely yours,

Redwood

## 1 Comment

Walter Roberson on 16 May 2013

Is there reason to expect that there is an algebraic solution? If not then you are going to have to do the substitution first and then do a numeric solution. You will likely have to do each set of values individually rather than the two sets together.

Answer by sami on 16 May 2013

inner matrix must agree

Answer by Redwood on 16 May 2013

Dear Sami,

What do you mean, "inner matrix must agree"?

Sincerely yours,

Redwood