# Julia performs badly for a single Mandlebrot creation

On `fortran90.org`

is a “Python Fortran Rosetta Stone”
page with a Mandelbrot
Set code comparison. I’m still learning Julia, so I tried to code a
similar short program using Julia.

Maybe I did something wrong… but for me, Julia took more CPU time, more memory, and more code verbosity than the Python example. For array masking, even Fortran was less verbose than Julia. Note that array masking is buildin for Numpy and Fortran; I did not try MaskedArrays.jl so probably the Julia code can be made less verbose, although that adds another dependency. I doubt if time and memory consumption can be brought down.

Language |
user |
system |
elapsed |
%CPU |
maxresident(k) |
---|---|---|---|---|---|

Fortran |
0.03 | 0.01 | 0:00.05 | 94 | 34280 |

Python |
2.47 | 0.03 | 0:02.53 | 99 | 121848 |

Julia |
3.94 | 0.20 | 0:04.10 | 100 | 503796 |

I did change the original code from `fortran90.org`

a bit
to make the algorithms even more similar (comparable). Below, the code
is shown as an image with a few comments – I hope you have a wide
monitor. All my files, code, scripts and whatnot are available as
download: mandelbrot_comparison.zip

*The very friendly people in the Discord chat channel “Humans of
Julia” made a few comments on my code, so I could learn and improve.
Thansk guys! (Updated code below the picture.)* Also see this gist!

**mandelbrot_improved.jl**

```
include("functions.jl")
# Const and type declarations didn't do much to make the code speedier,
# but they added a lot of verbosity to the code, so I removed those again.
= 100
ITERATIONS = 1000
DENSITY = -2.68, 1.32
x_min, x_max = -1.5, 1.5
y_min, y_max
= meshgrid(LinRange(x_min, x_max, DENSITY), LinRange(y_min, y_max, DENSITY))
x,y = x + (y)im
c = copy(c)
z = fill(255,DENSITY,DENSITY)
fractal
= [abs(α) ≤ 10 for α in z] # initial fill
mask # for loop contents improved by devin.jl
for n in 1:ITERATIONS
println("Iteration ", n)
= abs(z) ≤ 10
@. mask .^= 2
z[mask] .+= c[mask]
z[mask] abs(z) > 10 && fractal == 255] = 254 * (n-1) ÷ ITERATIONS
@. fractal[end
= log.(fractal) #devin.jl
logfractal
println("Saving...")
savetxt("fractal_jl.dat", logfractal)
savetxt("coord_jl.dat", [ x_min, x_max, y_min, y_max ] )
```

**functions.jl**

```
# meshgrid function by Chris Rackauckas, 2016
# https://groups.google.com/g/julia-users/c/83Pfg9HGhGQ/m/9G_0wi-GBQAJ
function meshgrid(a,b)
= a' .* ones(length(b))
x = ones(length(a))' .* b
y return x,y
end
# stylistic improvement by Jacob
savetxt(filename, array) = open(filename) do io
for row in eachrow(array)
= replace(string(row), "[" => "", "]" => "", "," => "")
line println(io, line)
end
end
```