How to display answers using polyfit

Hello everyone.

I'm trying to use polyfit to analyze some data, I want a linear regression, but the slope of the line is small, approximately 1.33e-7, but when I use polyfit, it only returns the coefficient of slope as 0. How can I get it to display the true number?

Answer 1

[Matt Fig]

How do you know the slop of the line before you do the fit? How noisy is the data?

This seems to work:

>> x = 0:1; y = [0 1.33e-7]+5;
>> pp = polyfit(x,y,1)

pp =

      1.33e-007            5

Answer 2

[Star Strider]

You may have scaling problems such that the slope and intercept may vary by several orders of magnitude. Experiment with:

format longE

to see if your regression coefficients will then display correctly. See format for details.

Answer 3

[Jan]

Perhaps you want to modify the display in the command line:

format long g