Output arguments not getting assigned?
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I keep getting the error Output argument "prime2" (and maybe others) not assigned during call to "sum_of_primes". Can someone explain why?
% This function takes an even integer greater than 2
% and expresses it as the sum of two prime integers
function [prime1, prime2] = sum_of_primes (num)
%%If input is an even integer greater than 2
if (mod(num,2) == 0) && (num > 2)
%%Initializing vector x to numbers from 1 to num
% any non-prime number is set to 0
for n = 1:num
if (isprime(n) == true)
x(n) = n;
end
end
%%Initializing vector z as array x without the zeros
% z will then be a vector of prime numbers
z = (x(x~=0))';
z = z<num;
%%Doing things and stuff
for n = 1:size(z)
prime1 = z(n);
if (isprime(num-prime1) == true)
prime2 = num-prime1;
break;
end
end
else
disp('Please enter an integer greater than 2.')
end
end
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更多回答（1 个）
for n = 1:size(z)
This will not do, what you expect, because size replies a vector. Better:
for n = 1:numel(z)
The line z = z<num let z be a logical vector. Most likely you mean:
z = z(z < num);
A simplification for the first loop:
v = 1:num;
x = v(isprime(v));
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