MatLab fiting eqaution to data

[2slowtogofast]

if i am given a data set of x and y values i need to come up with an expression of

x*y^a = b and b are constants

no idea how to get started any help geting started please

 

[viscousflow]

You may want to investigate the curve fitting toolbox

http://www.mathworks.com/products/curvefitting/description1.html

 

[2slowtogofast]

yeah i did polyfit(x,log(y),1)

that will return 2 number and ill have an eqn

lny = a1x+a2 it fit a straight line to my data but I am confused on what to do next i need xy^a = b is there another function i should try and use or is this more of an algebraic manipulation type of thing and if so can some one tell me where to start.

 

[viscousflow]

There is an algebraic way to solve that. Here is my approach

$$y^a = \frac{b}{x}$$

$$\log(y^a) = \log(\frac{b}{x})$$

$$a \log(y) = \log(b) - \log(x)$$

Since this is the homework forum I can't solve the entire problem for you. However, if you do some arranging you can do a $$y=mx+b$$ curve fit and solve for your coefficients.

 

[DeeNos]

First, it is important to understand the goal of fitting an equation to a data set. The purpose is to find an equation that best represents the relationship between the x and y values in the data set. In this case, we are looking for an equation of the form x*y^a = b, where a and b are constants.

To get started, you can use the curve fitting tool in MatLab. This tool allows you to easily fit an equation to your data set by selecting the appropriate function and adjusting the parameters to find the best fit. You can also use the "fit" function in MatLab, which allows you to specify the type of equation you want to fit and the data set.

It is important to note that there is no one "correct" equation to fit to a data set. The choice of equation will depend on the nature of the data and the relationship between the variables. It may be helpful to plot the data first to get an idea of the general shape and trend before attempting to fit an equation.

Additionally, it is important to consider the accuracy and validity of the equation you are fitting. The fit may look good visually, but it is important to also assess the statistical significance of the fit and any potential errors or limitations in the data.

In summary, to fit an equation to a data set in MatLab, you can use the curve fitting tool or the "fit" function, but it is important to carefully consider the nature of the data and the validity of the fit.