Plotting normal distribution with negative x range

When plotting a normal distribution using the pdf command, setting the x-value range to negative values seems to give me a wrong answer. Quite likely this is me misunderstanding the command but any help would be appreciated.

I obtain the parameters using the code:

   fit_parameters = fitdist(double(data_to_fit(:)),'Normal');

I then try plot it as follows:

   plot(pdf(fit_parameters,x_values)

Considering that the mean is just below 0, I've set my x-values to something like -80:80. What I get, however, is a curve centred at 80 which is obviously wrong.

I am using MatLab 2013

Thanks, Y

Answer 1

[John D'Errico]

When you call plot with ONE argument, it assumes that the x-axis is the integers, 1:numel(y). So, your expected x-axis would be 1:161. From what you have said, the mean will fall right around 80 as you plotted it.

Instead, try this:

plot(x_values,pdf(fit_parameters,x_values))

[Yonni f]

Jeez, thanks so much. There's nothing quite like banging your head against the wall for hours when the answer so simple!