Changing a single value inside a matrix4

[Whatsinaname]

I'm trying to change a value inside a matrix. This seems more complicated than I initially thought it was.

It's a standard 4x4 matrix. I want to change the values for row 4, fields 1-3.
Looking at the spreadsheet, the matrix is represented as an array of 16 values, therefore I tied:

 

4@matx[12] = 0.0;
4@matx[13] = 0.0;

//etc.

 ...which results in a VEX error 'Ambiguous call to array index operator'. Why? It's position 12 of that array, storing a float value I want to overwrite with a float value.

How that supposed to be done in VEX?

Edited March 19, 2020 by Whatsinaname

[Skybar]

You can use setcomp()

https://www.sidefx.com/docs/houdini/vex/functions/setcomp.html

[anim]

As docs say https://www.sidefx.com/docs/houdini/vex/lang.html

Quote

 

For matrices, you can use a pair of letters:

.xx to reference the [0][0] element

.zz to reference the [2][2] element

.ax to reference the [3][0] element

 

 

[Whatsinaname]

Thanks guys!