How would one find an expanding parallel line?

If I have two arbitrarily defined points (x1,y1) and (x2,y2). I would like to move these two points in a perpindicular direction, perpindicular to the line made by these two points. The distance moved is also a changing value, increasing with time. What is the easiest way to program this? I have done a series of finding the slope, inverting the equation, calculation the new points in a symbolically solved equation. The problem is this is a time consuming process for the code.

[Bob Thompson]

What part of the process is time consuming? I would think that finding slope and the inverted slope would be pretty simple. How are you calculating your new points? Can you just find all of the points at the same time in a matrix?

[John D'Errico]

A long time for the code to run? Seriously? Why are you using symbolic computations at all?

Answer 1

[David Hill]

rate=@(t)t^1.1;%make the rate what ever you desire with respect to time
function [e,f] = parallelExpansion(rate,t,a,b)%function provides points e,f that have been moved perpendicular to orginal points a,b with respect to rate and time
c=b-a;
m=-c(1)/c(2);
e=[a(1)+rate(t)*t,a(2)+m*rate(t)*t];
f=[b(1)+rate(t)*t,b(2)+m*rate(t)*t];
end