Ignoring NaN values in a function

I am trying to create a function to calculate an index consisting of 6 variables (x1,x2,x3,x4,x5,x6).

Any number of the following variables (x2,x3,x4,x5,x6) may have a value of NaN.

Example 1:

If x2 = NaN

I want exclude d2 from the index equation and divde it by squareroot of 5 insted of squareroot 6.

Example 2:

If x2 = NaN and x3=NaN

I want exclude d2 and d3 from the index equation and divde it by squareroot of 4 insted of squareroot 6.

In the below code I could set if isnan (x2) then d2=0 but I am not sure how to set the denominator = sqrt (n number of d).

How to code the function efficiently ?

function index = anna (x1,x2,x3,x4,x5,x6)

offset = 1;

d1 = (((1-x1).^2) * 0.5);

d2 = ((1-x2).^2);
d3 = ((1-x3).^2);
d4 = ((1-x4).^2);
d5 = ((1-x5).^2);
d6 = ((1-x6).^2);

index = (offset - ( sqrt ( (d1) + (((d2) + (d3) + (d4) + (d5) + (d6))* 0.5)))/ sqrt(6)); 
% "sqrt(6)" is n number of d

[Syed Anas Ahmed]

I have tried the following code but I am still getting NaN values and exact same answers as the above code.

Example Answers:

Index(n)=0.4756, 0.3644, NaN, 0.3443,...........

n=190

I am not sure where I am going wrong.

function index = anna(x1,x2,x3,x4,x5,x6)

offset = 1;

% If x2,x3,x4,x5,x6 is NaN then d2,d3,d4,d5,d6 should be 0 else d2 =
% ((1-x2).^2)..........

if isnan(x2), d2 = (0);
else ,d2 = ((1-x2).^2);
end

if isnan(x3), d3 = (0);
else ,d3 = ((1-x3).^2);
end

if isnan(x4), d4 = (0);
else ,d4 = ((1-x4).^2);
end  

if isnan(x5), d5 = (0);
else ,d5 = ((1-x5).^2);
end

if isnan(x6), d6 = (0);
else ,d6 = ((1-x6).^2);
end

d1 = (((1-x1).^2) * 0.5);

dn = 6;  %Total number of dimensions

%For every x2,3,4,5,6 that is NaN substract 1 from total dimensions

if isnan(x6)
    (dn(-1));
end

if isnan(x6)
    (dn(-1));
end

if isnan(x6)
    (dn(-1));
end

if isnan(x5)
    (dn(-1));
end

if isnan(x6)
    (dn(-1));
end

index = (offset - ( sqrt ( (d1) + (((d2) + (d3) + (d4) + (d5) + (d6))* 0.5)))/ sqrt(dn));

Answer 1

[Matt J]

function index = anna(x)  %x is vector of arbitrary length

  offset=1;

  d=0.5*(1-x).^2;
  
  index=offset-sqrt(mean(d,'omitnan'));
  
end

[Syed Anas Ahmed]

Thanks for the answer but each x variable has 190 diffrent values and some of them are NaN.

[Matt J]

Then you should pass in x as a 6x190 matrix. Code remains the same.