# Function does not calculate desired variable.

2 views (last 30 days)
Giuseppe on 20 May 2014
Commented: Friedrich on 21 May 2014
Hi I have the following function;
function [EV,N,t,S] = EVjc300293(EV,N,t,S)
% If a variable is set to zero calculate its value.
% 1. Choose which variable to process.
if EV==0
EV = log2((N^2)/t)-log2(S/100);
elseif N==0
N = sqrt((2^(EV+log2(S/100)))*t);
elseif t==0
t = (N^2)/(2^(EV+log2(S/100)));
elseif S==0
S = 100/(2^(EV-log2((N^2)/t)));
end
end
I want to make it so that if a variable is set to zero in the function its value is calculated. I wish to do this using the if elseif statements listed. However when I run it it always calculates EV and not any other variable?
Thanks.
Friedrich on 20 May 2014
How do you call it? Name some examples
Giuseppe on 20 May 2014
I call it like this;
[N] = EVjc300293(10,0,3,5)
Where here for example I am trying to find N?

Friedrich on 20 May 2014
N is your second output so you would need to call it like this:
>> [~,N] = EVjc300293(10,0,3,5)
Chandrasekhar on 21 May 2014
In this answer only N is being calculated since the if EV==0 condition has failed.. what abt others??
Friedrich on 21 May 2014
The other variables arent't calculated. Since output and input variables have the same name they are copied to the output variables. Your function always return 4 variables and you need to know/figure out which output variables are relevant for you:
[a,b,c,d] = EVjc300293(10,0,3,5)
You will see that a is 10, b got calculated and c is 3 and d is 5.

Chandrasekhar on 20 May 2014
In the function that you have written EV, N ,t,s are in separate if -else if conditions and only on of them executes at a time.
in you case if EV==0 is getting satisfied and hence only EV is being calculated and the else if and else conditions are not getting executed.
one solution is to assign a default value for all the value at the beginning of the function.
Giuseppe on 20 May 2014
Could you further explain this idea please?

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