If statement correction help

Hi I am trying to write an if statement. What I need is to create an array of 1000 random variables from -1 to 0 and 1/2 to 1. My algorithm is if the number in that element is less than 0 and greater than 0.5, move onto the next, if not repeat but doesn't not seem to work when I check the resulting array. Sorry if this may be rudimentary but so far I wrote:

X1 = zeros(1, 1e3);
for i=1:numel(X1);
    X1(i)=-1+(2)*rand(1);
    if X1(i) < 0 & X1(i) > 0.5;
         i=i+1;
    else
        i=i;
    end
end

Thank you so much, I appreciate the help.

[madhan ravi]

flip the direction of relational operators and use && instead of &

[Walter Roberson]

It is not possible for a number to be sumultaneously less than 0 and greater than 1/2 . You might want to use | instead of & or you might want to use > and < instead of < and >

Note that any change you make to a loop control variable such as i inside the loop will be ignored on the next iteration of the loop. You cannot cause a particular for iteration to repeat by adjusting the loop control variable. Consider using while

Answer 1

[per isakson]

"I need is to create an array of 1000 random variables from -1 to 0 and 1/2 to 1"

Another approach

>> X1 = rand(1,1e3)*1.5 - 1;
>> X1(X1>0) = X1(X1>0)+0.5;
>> plot(X1,'.')

or to get the "same" number of elements in each interval

>> X1 = rand(1,1e3)*2 - 1;
>> X1(X1>0) = X1(X1>0)/2 + 0.5;
>> plot(X1,'.')