divide area under Histogram

Hello,

I have the following histogram (normalised to maximum frequency) as shown:

http://i49.tinypic.com/313hj40.png

How can I find the total area of the curve say area_tot from [-1 to +1] under the histogram and then only the areas from [-1 to -0.2] say area_1 and [+0.2 to +1] say area_2 ??

Please help.

Answer 1

[Sean de Wolski]

doc trapz

[zozo]

Yes, I have found the solution. But what is the correct way of normalising any histogram?

1) normalise by max. freq 2) normalise by total area 3) normalise by sum of freqs?

Please advice.