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Re: adding up consecutive elements [message #3366]

Thu, 19 January 1995 17:52

rivers
Messages: 228
Registered: March 1991

Senior Member

In article <3fk5ps$emd@itssrv1.ucsf.edu>, aki@scifi.ucsf.edu (Andreas Kiefer) writes:
> I need to add consecutive elements of an array. total() doesn't do it because it gives me the sum of the hole array or at least the sum over the different rows/columns if the dimension keyword is used.
> I could use a loop like
>
> for i=0,n_elements(array)-1 do sum(i)=sum(i-1)+array(i)
>
> But this is really slow for large arrays.
>

I have asked RSI for a this function in the past.

A simple derivative function in IDL is just

IDL> d = array - shift(array, 1)

What we are asking for is the inverse of this, i.e. a simple integral or running
total.

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Re: adding up consecutive elements

By: rivers on Thu, 19 January 1995 17:52

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