Stop value in loop for repeating

clc;

clear;

close all;

rng('shuffle');

myint = randi([4,100]);

while mod(myint,2) ~= 0

myint = randi([4,100]);

end

fprintf('%d is the sum of these prime numbers\n',myint);

myprime = primes(myint);

mylength = ceil(length(myprime)/2);

for i=1:length(myprime)

for k=1:length(myprime)

if(myprime(i)+myprime(k)== myint)

num1 = myprime(i);

num2 = myprime(k);

fprintf('%d = %d + %d \n',myint,num1,num2)

end

end

end

i am trying to create the goldbach conjecture but I do not want the prime numbers that have already been listed to repeat. eg 7+5 and 5+7.

Answer 1

[James Tursa]

Not sure if you need the numbers to be different or not. Either this:

for k=i:length(myprime)

or this

for k=i+1:length(myprime)

[Pallav Patel]

Thank you james. Both of them work perfectly. Could you please elaborate more as I am trying to understand the code

[James Tursa]

This simply forces myprime(k) to be greater than (or equal to depending on which code you use) the value of myprime(i). So you will never get both the 5 + 7 and the 7 + 5 choices.