Neat representation of results in Julia after a loop - julia

Question

I have created a small code in Julia that is able to use function iteration to solve a simple non-linear problem.
The code is the following:
"""
Problem: find the root of f(x) = exp(-x) - x
using the fixed point iteration
(aka function iteration)
Solution: f(x) = exp(-x) - x = 0
x = exp(-x)
"""
i = 0; # initialize first iteration
x = 0; # initialize solution
error = 1; # initialize error bound
xvals = x; # initialize array of iterates
tic()
while error >= 1e-10
y = exp(-x);
xvals = [xvals;y]; # It is not needed actually
error = abs(y-x);
x = y;
i = i + 1;
println(["Solution", x', "Error:", error', "Iteration no:", i'])
end
toc()
In the above code the results are not neat for there are many decimal numbers. To my understanding, using println may not be a good idea and instead #printf or sprintf must be used, however, I was not able to put everything in one line.
Is it possible to do that?

Answer 1

The syntax for printf is (roughly) the same for all languages,
but it is indeed arcane.
You can use %f for floats, %e for floats in scientific notation,
%d for integers, %s for strings.
The numbers between the % and the letter are
the number of digits (or characters) before and after the comma.
i = 0
x = 0
error = Inf
while error >= 1e-10
x, previous = exp(-x), x
error = abs( x - previous )
i += 1
#printf(
"Value: %1.3f Error: %1.3e Iteration: %3d\n",
x, error, i
)
end
You could also have tried round or signif,
but since round decimal numbers cannot always be represented exactly as floats,
that does not work reliably.