Function for power regression

i wanted to use power regression for values of vibrating mass equation:

the values are:

m=[0.0200 0.5000 0.1000 0.1500 0.2000 0.2500 0.3000 0.3500 0.4000]
T=[0.2000 0.3100 0.4600 0.5300 0.6200 0.7100 0.7600 0.8400 0.9100]

but i can't figure out that right function for power regression, would apprecaite some help

[David Goodmanson]

Hi Shatha,

First of all you need to fix the second value of m, which should be .0500 not .5000.

If T is proportional to sqrt(m), then T^2 is proportional to m. So

plot(m,T.^2,'-o')

shows a nice straight line (almost) which you can fit with linear regression.

[Shatha]

thank you for pointing out the error in the second value i missed that, i am still looking though for a function that gives me the values of a and b such that for a power regression model

Answer 1

[David Hill]

 g=fit(m',T','a*x^b','StartPoint',[.02 .2]);

[Shatha]

this worked!

thank you very much