# Question:How to plot the range of a complex function depending on two variables?

## Question:How to plot the range of a complex function depending on two variables?

Maple 2020

So I have a complex-valued function f that depends on two real variables x and y. I want to plot its range, i.e. the set of all values f(x,y), where x and y vary over their entire domain (which is a compact subset of R^2). Since I did not find of a direct way to do this, I decided to just compute the output f(x,y) at a finite set of points and plot these values in the complex plane. This gives me a rough idea of what the range should look like. However, this process is very slow (even though it should not be that slow, in my opinion). Here is the code I have used:

```f := x -> exp(2*I*Pi*x);
S1 := (x, y) -> Matrix(3, 3, [[f(x - y), 0, 0], [0, 1, 0], [0, 0, f(-y)]]);
S2 := (x, y) -> Matrix(3, 3, [[f(y), 0, 0], [0, f(y - x), 0], [0, 0, 1]]);
C := Typesetting[delayDotProduct](1/sqrt(3), Matrix(3, 3, [[1, 1, 1], [1, f(1/3), f(2/3)], [1, f(2/3), f(1/3)]]), true);
with(LinearAlgebra);
d := LinearAlgebra[Determinant](C . C);
V := (x, y) -> (((S1(x, y)/d^(1/3)) . C) . (S2(x, y))) . C;
tracevals := [];

for i from 0 to 100 do
for j from 0 to 100 do tracevals := [op(tracevals), Trace(V(0.01*i, 0.01*j))]; end do;
end do;
with(plots);
P2 := complexplot(tracevals, x = -2 .. 3, y = -3 .. 3);
```

Note that the specific example (i.e. plotting the trace of a unitary matrix V(x,y)) is not really important to this question. We could instead think of any complex-valued function f(x,y), it should not have any impact on the problem. Maple generates the following output:

Even though this output shows quite well the range that the function will take, it takes almost two minutes to generate. Is there a quicker or more elegant way to compute the range of a function?

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