Re: Statistics of a histogram

[Carlo de Falco]

On 30 Jan 2009, at 18:44, Shaun Jackman wrote:

> Hi,
>
> I have a matrix representing samples of data [x n] meaning that x(i)
> was observed n(i) times. Are there functions to calculate the
> statistics of observations in this format? I can calculate the mean
> easily enough:
> sum(x .* n) / sum(n)
>
> How do find the pth percentile?

assuming

a = [ x1,n1; x2,n2; ... ];

I beleive you could do something like:

nn = cumsum(a(:,2));
nn /= nn(end);
xp = max( a(nn<p/100,1) )

but I'm sure there is some octave-forge function to do this, have you  
looked at the statistics package?

> Cheers,
> Shaun

c.