Relplot: a general equation plotter

Relplot constructs high-resolution PostScript or PDF plots of the solutions to equations on two variables. Unlike most other plotters, it can handle general equations, not just functions. It can handle inequalities, and it can plot multiple equations at once, separated by commas.

What can you plot?

• Separate formulas with commas: ,
• Logical operators for combining formulas: && & ||
• Relational operators: = < <= > >=
• Binary arithmetic ops: + * - / ^ mod
• Unary arithmetic ops: |x| sqrt floor
    exp ln sin cos tan asin acos atan atan2
    sinh cosh tanh
• Variables: x y r th
• Constants: pi e

x^3 + y^3 = 3xy,  r^2 = 9/2

Some interesting equations to try:

x^2 * y^2 = 1                            x^3 + y^3 = 3xy
x^y = y^x                                (r-1/2)^5 = 4yx^3 - 4xy^3
ln r = sin 4x^2 + cos 5y^2 + x/4         ((xy(x-y)(x+y)(x^2+y^2-4))^2 - 1) < 1
y>|x| & y<sqrt(exp x + exp(-x) - 2)      y = 3 * x * sin(pi/r)
x^2 <= floor|2y|, x^2>|2y|               (x^2 - y^2) mod 1 = xy mod 1
(5x mod 1 = 0 || 5y mod 1 = 0) & r<2     x+y < sin (5x-5y) && |x| < 1, |x| > 1