This function is supposed to return a point on a quadratic function, but it doesn't work right.

function launch(h,v,t)
return -(v*t^2)/h^2+(2*t*v)/h
end

Whenever I call this:

for i=0,80 do
pset(i,launch(40,40,i),8)
end

It appears like this:

Did I do something wrong, or is this a fault of how Pico-8 works?