Search code examples
juliaoctave

How to translate this Octave code to Julia?

I want to make a logistical map in Julia and I am having difficulties. I already know how to do it in Octave, how could I turn this code to Julia? My difficulty is mainly in the "map [i,:]" part.

#Creates a vector of initial conditions and "r"
x=rand(150,1);
r=(2.51:.01:4);

#Transpose the r
r=r';

#Makes 300 times the product of each element of r for each element of x
for i=1:300
x=r.*x.*(1-x);
end

#Makes 200 times the product of each element of r for each element of x and stores each value of x on line i of the "map" matrix
for i=1:200
x=r.*x.*(1-x);
map(i,:)=x;
end

#Plots each column of the map for each element o r
plot(r,map,'.')
Solution

  • I haven't written julia in a while so there may be more efficient ways of doing this now, but here is a more or less direct equivalent to your octave code.

    using PyPlot

x = rand( 150, 1 );
r = reshape( 2.51:.01:4, (:, 1) );

for i in 1:300
    global x
    x = r .* x .* (1 .- x);
end

Map = Matrix{Float64}(undef, 200, 150);

for i in 1:200
    global x, Map
    x = r .* x .* (1 .- x);
    Map[i:i,:] .= transpose(x);
end

for i in 1:length(r)
   plot( r, Map[i,:], "." )
end