topic Re: Calculation of the mean in an Array in Mathcad

Calculation of the mean in an Array

DG_8871348 — Mon, 07 Jun 2021 16:38:00 GMT

Hi,

I have a simple Problem however I'm searching since nearly one hour for the solution.

I'm looking to calculate the mean in an Array. I Have R=(x1, x2, ....) and i want to calculate the mean of every value in the Array like Rm1=(x1+x2)/2 Rm2=(x2+x3)/2 ... and so on.
How does it work im Mathcad? The normal Matrix Indicies with i and i+1 doesn't work.

I also attached a short Version of the Mathcad file, especially to focus on this Problem. Thanks for helping 😊

Re: Calculation of the mean in an Array

LucMeekes — Mon, 07 Jun 2021 17:54:32 GMT

You do realise that the result of this operation produces an array that has one less elements...?

This is one way to do it:

The result for your array is:

There's also a built-in function for it: Moving average. Try:

movavg(Ri,2)

Success!
Luc

Re: Calculation of the mean in an Array

DG_8871348 — Mon, 07 Jun 2021 18:00:41 GMT

Thanks for the fast Reply.
But is there any shorter and easier Solution for this Problem without Programming?

Re: Calculation of the mean in an Array

LucMeekes — Mon, 07 Jun 2021 18:04:51 GMT

Look again to my post: movavg is built in.

Success!

Luc

Re: Calculation of the mean in an Array

Werner_E — Tue, 08 Jun 2021 09:05:02 GMT

Here is your own approach using a range variable, but as the last element of the vector has no successor, the range to use must run only up to Anz.i-1 and so you can't use i, you need a new range variable - k in my example (but of course you also could redefine i for that purpose).

Nonetheless I would prefer defining a small utility function

But is there any shorter and easier Solution for this Problem without Programming?

Luc's "Mean2" function IS quite short (and can be written even a little bit shorter if you assume ORIGIN=0) does NOT use programming (so it could be used in the free Express version of Prime, too).

The built-in function "movavg" suggested by Luc makes the same calculations but always returns a vector of the same length by prepending first vector element.

To get rid of it you may use the "submatrix" command

(assuming ORIGIN=0 as is the case in your sheet).

Re: Calculation of the mean in an Array

DG_8871348 — Tue, 08 Jun 2021 21:17:46 GMT

Thanks, the first Example was the Perfect Solution 😎