A query relating a function with 3 input arguments.

My code is:

function i = Three_inputsFunction (x,y,z)

if x>y>z || y>x>z

x+y

elseif x<y<z || x<z<y

y+z

else

x+z

end

end

>> Three_inputsFunction (-18,-3,-6)

ans =

-21

Query : Why is the answer '-21' and not '-9'?

Answer 1

[Stephen23]

"Why is the answer '-21' and not '-9'?"

Because this code

x>y>z

is parsed from left to right as

(x>y)>z

which (because true==1 and false==0) is equivalent to either of these

1>z
0>z

You need this instead:

x>y && y>z

Also note that you do not define the function output i.

[Stephen23]

Fixed it for you too:

Three_inputsFunction (-18,-3,-6)

ans = -9

function Three_inputsFunction(x,y,z)
if x>y && y>z || y>x && x>z
    x+y
elseif x<y && y<z || x<z && z<y
    y+z
else
    x+z 
end
end

[Alek Poudel]

i see, understood.

but confused with your 2nd elaboration :

1>z

0>z

Would you mind detailing me please. I am new to Matlab.

Thanks for your quick reply though. :)

[Stephen23]

"Would you mind detailing me please."

This comparison

x>y

can return either

true

or

false

so your code (I added the parentheses for clarity, but these do not change the order of operations):

(x>y)>z

will give either of these two situations:

(true)>z
(false)>z

or using the equivalent numeric values (in MATLAB true==1 and false==0):

(1)>z
(0)>z

from which we can trivially remove the parentheses:

1>z
0>z

So you thought you were performing a comparison of three variables, but in reality you were actually just comparing z against zero or one. The rules of precedence explain why.

[Alek Poudel]

Alright, many thanks!

[Stephen23]

@Alek Poudel: you can also show your thanks by accepting my answer :)

[Alek Poudel]

ohh yeah, done! didn't know about that before. Cheers!