Format of mat file

[Rich Lakey]

just getting started and have

M=csvread('file.csv')

  and then

save('file.mat','M')

File looks ok but cannot find description of what it should look like. 
First few lines:

# Created by Octave 4.2.2, Tue Dec 25 15:27:10 2018 CST <address@hidden>
# name: M
# type: matrix
# rows: 1258
# columns: 1
 1833.3199
 1842.02
 1841.4
 1841.0699

The data starts in column 2 or is the first column zero?  Should my data 
be in the fist column? Do I reference data starting in row 1 or 6 after 
the header info. I'm assuming Octave skips the header info and treats 
row 6 as 1.

My program seems to run ok but no output. I suspect I am not reading the 
data from the file. Using a blank file the results are the same, program 
runs but no output.

The start of my program loads the file as:

% Part 1
load file.mat
for i=1:1258
x(i) = i;
end
p1 = polyfit(x', file(1:1258), 3);
xx = (1:1:1358)';
pp1 = polyval(p1, xx);
plot(xx, NFLXdata)
hold

I can run commands and get the samples in documentation to work, but I 
am missing something with inputting data from file.

Rich