Why is it doing all 100 attempts as a singular go?

I am working on a bit of code to generate a the probability of an item dropping. I have it set so that its going through an if loop chain, where if it isnt one thing it goes to the next thing and if it isnt that it goes to the next and so forth, but when I try to run it with a for loop to dictate how many times it needs to run it just gives all of the attempts to a singular output giving that one output a probability of 100% each run, which isnt whats supposed to happen.

numOfSims = 100;
potionOfStrength = 0;
braceletOfStrength = 0;
hammerOfThunder = 0;
none = 0;
X = rand;
X2 = rand;
X3 = rand;
   
for iteration_num = 1:numOfSims

    if X<0.4
        potionOfStrength = potionOfStrength +1;
    else
        if X2<0.2
            braceletOfStrength = braceletOfStrength +1;
        else
            if X3<0.2
                hammerOfThunder = hammerOfThunder +1;
            else
                none = none +1;
            end
        end
    end

This is the code I've been working on.

Answer 1

[Voss]

Your code does the same thing 100 times because the random values don't change from one iteration to the next.

I guess you would want to generate new random X, X2, and X3 in each iteration of the for loop:

numOfSims = 100;
potionOfStrength = 0;
braceletOfStrength = 0;
hammerOfThunder = 0;
none = 0;
   
for iteration_num = 1:numOfSims
    
    X = rand;
    X2 = rand;
    X3 = rand;
    
    if X<0.4
        potionOfStrength = potionOfStrength +1;
    else
        if X2<0.2
            braceletOfStrength = braceletOfStrength +1;
        else
            if X3<0.2
                hammerOfThunder = hammerOfThunder +1;
            else
                none = none +1;
            end
        end
    end
    
end

potionOfStrength

potionOfStrength = 36

braceletOfStrength

braceletOfStrength = 16

hammerOfThunder

hammerOfThunder = 6

none

none = 42

Or make X, X2, and X3 random vectors of length numOfSims (i.e., 100), and index them inside the loop:

numOfSims = 100;
potionOfStrength = 0;
braceletOfStrength = 0;
hammerOfThunder = 0;
none = 0;

X = rand(1,numOfSims);
X2 = rand(1,numOfSims);
X3 = rand(1,numOfSims);
    
for iteration_num = 1:numOfSims
    
    if X(iteration_num)<0.4
        potionOfStrength = potionOfStrength +1;
    else
        if X2(iteration_num)<0.2
            braceletOfStrength = braceletOfStrength +1;
        else
            if X3(iteration_num)<0.2
                hammerOfThunder = hammerOfThunder +1;
            else
                none = none +1;
            end
        end
    end
    
end

potionOfStrength

potionOfStrength = 37

braceletOfStrength

braceletOfStrength = 13

hammerOfThunder

hammerOfThunder = 13

none

none = 37

In either case, you can utilize elseif to shorten your code, e.g.:

for iteration_num = 1:numOfSims
    X = rand;
    X2 = rand;
    X3 = rand;
    if X<0.4
        potionOfStrength = potionOfStrength +1;
    elseif X2<0.2
        braceletOfStrength = braceletOfStrength +1;
    elseif X3<0.2
        hammerOfThunder = hammerOfThunder +1;
    else
        none = none +1;
    end
end

or:

for iteration_num = 1:numOfSims
    if X(iteration_num)<0.4
        potionOfStrength = potionOfStrength +1;
    elseif X2(iteration_num)<0.2
        braceletOfStrength = braceletOfStrength +1;
    elseif X3(iteration_num)<0.2
        hammerOfThunder = hammerOfThunder +1;
    else
        none = none +1;
    end
end

[Larose]

I completely forgot I hadn't moved it to be nested in the for loop, thank you so much, my brain is shot lol

[Voss]

You're welcome!