Interpolation / Curve fitting / Empirical formula

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satendra kumar
satendra kumar on 16 Nov 2011
Hii, I have an Eq.- M=A[P^a]*[Q^b]*[R^c] From experiments the value of M,P,Q,R is known to me. Now i need to find the value of A,a,b,c... Can anyone tell me how to solve this problem

Answers (1)

Andrew Newell
Andrew Newell on 17 Nov 2011
Take the logarithms of both sides, so you have a linear regression problem. How you solve that depends on whether you have the Statistics Toolbox.
  2 Comments
Andrew Newell
Andrew Newell on 17 Nov 2011
If you take the logarithms, you get:
log(M) = log(A) + a*log(P) + b*log(Q) + c*log(R).
That's a linear equation, equivalent to
y = r +a*x1 + b*x2 +c*x3.
That's a linear equation in the variables y=log(M), x1=log(P), etc., and there is certainly no requirement that r, a, b and c be integers.

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