Help with if, else if & else statements

I am working on the following question for a class. Write a function called fare that computes the bus fare one must pay in a given city based on the distance travelled. Here is how the fare is calculated: the first mile is $2. Each additional mile up to a total trip distance of 10 miles is 25 cents. Each additional mile over 10 miles is 10 cents. Miles are rounded to the nearest integer other than the first mile which must be paid in full once a journey begins. Children 18 or younger and seniors 60 or older get a 20% discount. The inputs to the function are the distance of the journey and the age of the passenger in this order. Return the fare in dollars, e.g., 2.75 would be the result returned for a 4-mile trip with no discount.

So far I have written the following but when I run the debugger I keep getting messages about my ends not being in the correct location. I have fiddled with moving the code around with the if, else and else if statements, but I seem to be missing something.

function f = fare(dm,ay)

dm = round(dm);

    if (dm <= 1)
        f = 2;
    
else if (dm> 1 && dm >= 10)
      f = 2 + (dm-1) * 0.25;  
      
else if (m > 10)
      f = 2 + ((dm-1) * 0.25) + ((dm-10)* 0.10);
        
if (ay <= 18 || ay >= 60)
       p = f(.80);            
else 
    p = f; 
            
end    

Answer 1

[Walter Roberson]

You are using else if as if it was elseif

That is,

if condition1
    action1
else if condition2
        action2
end

is not valid. Valid would be

if condition1
    action1
else if condition2
        action2
end
end

which is equivalent to

if condition1
    action1
else
    if condition2
        action2
     end
end

Also legal is

if condition1
    action1
elseif condition2
    action2
end

Notice there is only a single end

You are probably wondering what the difference is between them. Well suppose you had

r = rand;
if r <= 1/2
    disp('first half')
else if r <= 3/4
        disp('third quarter')
end
disp('another message')
end

Then when we space it better, we get

r = rand;
if r <= 1/2
    disp('first half')
else
    if r <= 3/4
        disp('third quarter')
    end
    disp('another message')
end

and you can see that 'another message' sent out as long as r <= 1/2 is false, including if r <= 3/4 is ture. But if we had

r = rand;
if r <= 1/2
    disp('first half')
elseif r <= 3/4
        disp('third quarter')
end
disp('another message')

then "another message" is always sent out.

Answer 2

[Image Analyst]

Ah, our old friend - the bus fare homework question.

Have you checked out all the other answers for this? Try that first before we go over it yet again.

Click for The Bus Fare Homework Problem

[Hilary Gaiser]

Oh, I have spent the whole evening looking over similar questions but I can’t quite seem to grasp it. I would like to have a better understanding of what I am doing wrong rather than just have someone help me fix my code.