[Scilab-users] Loop query

[Lester Anderson]

Hello Samuel,

The size of ns (number of steps) and seq (sequence of values) are variable
depending on the integer input, and this seems to be one issue. So I guess
the problem is how to allocate dynamic arrays where you do not know the
final size?

This is a direct translation of a Matlab function:

function [ns, seq]=collatz(n)

// Translation of Matlab function// First number in the sequence is
nseq(1) = n;// Position an index on the next element of the sequencei
= 2;
// Repeat the iteration until you find a 1while seq(i-1) ~= 1
    // Use a modulus after division to find an even/odd number
    if modulo(seq(i-1), 2) == 0
        // Step taken if even
        seq(i) = seq(i-1)/2;
    else
        // Step taken if odd
        seq(i) = 3*seq(i-1) + 1;
    end
    // Increment index
    i = i+1;end// Find the length of the sequencens = length(seq);endfunction


Lester

On Sun, 15 Aug 2021 at 09:24, Samuel Gougeon <sgougeon at free.fr> wrote:

> Le 15/08/2021 à 09:00, Lester Anderson a écrit :
>
> Hello,
>
> Basic query. I have a simple code that applies the Collatz conjecture
> equation (3n+1) by running a function and then runs a loop over the values
> stored in prime (the first 8 Prime numbers):
>
> clear
>
> exec('collatz.sci',-1);
> prime = primes(20);
> for i = 1:length(prime)
>     [ns, seq]=collatz(prime(i))end
>
> As it stands, this just runs to the end (i=8) and the value 19. How can I
> get the code to write the results of each loop pass into the variables ns
> and seq, such that each contains the results of the 8 passes?
>
>
> This runs all the 8 iterations, but each next iteration overwrites ns and
> seq.
> What are the sizes of ns and seq ?
>
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