topic Re: Shift values in matrix in Mathcad

Shift values in matrix

PZ_9812318 — Wed, 07 Apr 2021 08:15:19 GMT

Hey, I liked to know how to shift the values at matrix by a certain value like this.

I have script in MathCad and matrix with hundreds values, and I need it to work automaticly. Thanks for help.

Re: Shift values in matrix

LucMeekes — Wed, 07 Apr 2021 08:39:09 GMT

Success!
Luc

Re: Shift values in matrix

PZ_9812318 — Wed, 07 Apr 2021 09:26:21 GMT

Thanks a lot, it works, you are very kind.

Re: Shift values in matrix

Werner_E — Wed, 07 Apr 2021 11:48:57 GMT

Here are my 2 cents

In contrary to Luc's "Mrot", my "Mshift" uses programming and therefore does not work in the limited Prime Express version. Also notice that Mrot and Mshift rotate/shift in different directions.

Doubling the data by stacking the matrix on top of itself is bold and may be considered inefficient, but this should not be a problem with matrices of just a few hundreds of rows 😉

You may also use the same function to shift both rows and columns:

P6 worksheet attached

Re: Shift values in matrix

MSheykman — Thu, 08 Apr 2021 15:09:05 GMT

It can be with built in functions:

Re: Shift values in matrix

MSheykman — Thu, 08 Apr 2021 15:13:31 GMT

Or just by mangling with indices as follows:

Re: Shift values in matrix

MSheykman — Sun, 11 Apr 2021 06:13:11 GMT

Or a pure math solution:

Re: Shift values in matrix

LucMeekes — Sun, 11 Apr 2021 13:39:11 GMT

Yes, there are multiple roads that lead to Rome.

I guess that for shifting/rotating the rows of a vector or matrix, first filling an nxn matrix is a bit overdone. Besides, this method doesn't work (as intended) for shifting/rotating rows of matrices....

Luc

Re: Shift values in matrix

Werner_E — Sun, 11 Apr 2021 14:55:26 GMT

@LucMeekes wrote:

Yes, there are multiple roads that lead to Rome.

I guess that for shifting/rotating the rows of a vector or matrix, first filling an nxn matrix is a bit overdone. Besides, this method doesn't work (as intended) for shifting/rotating rows of matrices....

Luc

I agree that the way the idea was presented isn't very practical for actual use.

But the principle can be turned into a convenient utility function which works on the rows of matrices, too 😉

Because the "matrix" function ignores the setting of ORIGIN, the function should also be ORIGIN-aware.

On the other hand ... it seems that @PZ_9812318 is no longer interested in his question. 😞

Re: Shift values in matrix

MSheykman — Mon, 12 Apr 2021 09:41:39 GMT

It is possible to generate the rotation matrix if you do not feel like filling it in with 0 and 1 manually.

If you need to populate a sparse matrix - you only need to set the values that are not equal to 0, others will become zero automatically. The dimension is defined by the largest row and column indices that you used while assigning values to specific elements.

j in the example contains an expression of i, that define how elements will be reordered.