How can i increase significant digits beyond 5 in basic fittings option in Matlab?

I have plotted data as shown in black dotted curve. I tried to find fitting using tools>basic fittings. Select 6th degree polynomial and tich show equations But here I can see only upto 5 significant digits. How can I get equations with more than 5 significant digits using basic fittings option?

[Ankit Chauhan]

I have used polyfit command,

coeff = polyfit(xdata, ydata, n); % n is degree of polynomial that fits well,

filename = ['Exact_coeff'];

xlswrite(filename, coeff); % this give me exact coeffiecient with all decimal places data.

[Image Analyst]

Well of course. The variables are always at full resolution. We thought you were talking about how you wanted more significant digits in how the numbers were displayed on your graph. For that you'd use sprintf() like I showed you in my Answer below.

Answer 1

[Image Analyst]

I'm not sure your equation reflects what was plotted. But anyway to get more decimal places in the text you can just use %.8f, (to get 8 decimal places) like

str = sprintf('y = %.8f * x^2 + %.8f * x^5 + ........................etc

text(xt, yt, str);

To get more decimal places along the y axis, use ytickformat():

% Test data:
x = linspace(0, 4, 1000);
y = -2.0365*x .^ 6 + ...
    20.52 * x .^ 5 + ...
    -74.37 * x .^ 4 + ...
    108.18 * x .^ 5 + ...
    -36.839 * x .^ 6 + ...
    8.7963 * x + ...
    -1.8823e6...
    ;
plot(x, y, 'b-', 'LineWidth', 2, 'MarkerSize', 30)
grid on;
% Show current format
fmt = ytickformat

fmt = '%g'

% Set y tick label format to be
ytickformat('%.8f')