How would I do this using matrix math?

I want to get the transformed position of the camera. (I'm removing the light position & rotation from the camera right?)

lx#=EntityX#(light,1)
ly#=EntityY#(light,1)
lz#=EntityZ#(light,1)
lpitch#=EntityPitch#(light,1)
lyaw#=EntityYaw#(light,1)
lroll#=EntityRoll#(light,1)

camx#=EntityX#(cam,1)
camy#=EntityY#(cam,1)
camz#=EntityZ#(cam,1)
cpitch#=EntityPitch#(cam,1)
cyaw#=EntityYaw#(cam,1)
croll#=EntityRoll#(cam,1)
			

EntityParent cam,light,True

PositionEntity light,0,0,0
RotateEntity light,0,0,0

;Grab the cameras transformed matrix (GetMatElement..)
GetEntityMat cmat,cam

;Unparent the camera, reposition cam & light
EntityParent cam,0
;put the light back where it was
PositionEntity light,lx,ly,lz,1
RotateEntity light,lpitch,lyaw,lroll,1
PositionEntity cam,camx,camy,camz,1
RotateEntity cam,cpitch,cyaw,croll,1

Do you need the position of the camera relative to the light?

tformpoint enityx( cam, 1 ), entityy( cam, 1 ) , entityz( cam , 1 ) , 0 , Light

tformedx, y & z are the coords relative to the camera

Probably barking up the wrong tree as I'm not sure what you mean. Apologies if that's the case.

Stevie