Keep getting error in polyfit

>> x = table2array(Test1_x);
>> y = table2array(Test1_y);

I keep getting this error in polyfit. Here is the code and output from Matlab during a simple test. x and y should be arrays of real numbers.

-----------------------------------------
>> poly_fit_coef = polyfit(x, y, 1);
Error using ones
CLASSNAME input must be a valid numeric class name.

Error in polyfit (line 59)
V(:,n+1) = ones(length(x),1,class(x));
--------------------------------------

What is wrong here?

Thanks in advance for any help!

Jennifer

Answer 1

[JFz]

I just got it! My x and y arrays have strings in them. I converted the strings to numbers and it worked!

x_d = str2double(x); y_d = str2double(y); poly_fit_coef = polyfit(x_d, y_d, 1);

[JFz]

Thanks to Image and Star both for the help.

Answer 2

[Image Analyst]

What does this say?

whos x
class(x)
whos y
class(y)
which -all polyfit

[JFz]

Thank you so much for your quick reply. I typed the commands and here are results: whos x Name Size Bytes Class Attributes

x         1000x1             126012  cell   
which -all polyfit
C:\Program Files\MATLAB\R2014b\toolbox\matlab\polyfun\polyfit.m

[Image Analyst]

Like I thought, it wasn't a vector of numbers, but of strings.

[Star Strider]

Well, all it said was ‘cell’. That could be anything.

[Image Analyst]

True. Since it came from table2array(), and we knew it wasn't a double, single, or an integer because it said "CLASSNAME input must be a valid numeric class name.", the most likely option that it would be is a cell array. Any cell array would generate this error - a cell array of strings, doubles, integers, etc.