I watching this episode now and want to address Casey's complaints about math solving software. I can recommend using
SageMath open-source software for that. No need to pay hundreds of dollars for expensive math packages if all you want is to solve simple equations. You can download it for using offline, but note that it is pretty big, because it is built on top of other open-source software. Another option is to use its online version which might be slow, because they offer it for free.
In my previous job our researchers did a lot of work with SageMath mostly focused on number theory for crypto stuff.
As for our ray intersection solution, you can enter following program and press "Run" button to execute it:
| var('pax,pay,rax,ray,pbx,pby,rbx,rby,ta,tb')
eq1 = pax + ta*rax == pbx + tb*rbx
eq2 = pay + ta*ray == pby + tb*rby
solve([eq1,eq2],[ta,tb])
|
Pretty simple. And this is how the result will look like:
https://cloud.sagemath.com/projec...b7/files/2017-02-19-214708.sagews
| [[ta == -((pay - pby)*rbx - pax*rby + pbx*rby)/(ray*rbx - rax*rby),
tb == -((pay - pby)*rax - pax*ray + pbx*ray)/(ray*rbx - rax*rby)]]
|
I believe SageMath uses
Maxima software for solving this, so you might be able to install only Maxima, instead of whole SageMath if you care about installing something smaller.