Multiply Matrix and Point to apply transformation

p5.js Coding Questions
1

openframeworks has makeRotationMatrix, makeTranslationMatrix, etc. and apply it to any stored coordinate.

p5js has applyMatirx() but it applies to the elements being drawn not to variables.
It seems http://glmatrix.net might have those options.

I was not successful using these examples https://developer.mozilla.org/en-US/docs/Web/API/WebGL_API/Matrix_math_for_the_web
and do var new_p = MDN.multiplyMatrixAndPoint(transformMatrix_0, old_p);

I ultimately want to loop through a bunch of coordinates and angles collect rotation and translation matrices and apply those later.

thanks for any advice.