Ignoring NaN values when multiplying?

I need to multiply a range of elements with eachother, and now i discovered that if any of the elements is entered as NaN, the entire product will be NaN.

winnerportfolios=zeros(11,127);                                  
for column=1:127                                                       
y=2;                                                               
    x=firstWinnerRow(1,column);                                        
    for col=2:3:375
        for nrStocks=10:10:100                                                 
            winnerportfolios(y,column)=prod(HPRsorted(x:x+nrStocks,col));
            y=y+1;
        end
    end
end

I'd like to find a way to ignore the NaN values. The only way i come to think of would be to change the NaN-values to 1...

Thank you so much in advance!

oh and ignore the awful code, I've been working with matlab for only about a month :)

[Federal Cearpa]

Turn all the Nan's into 1's.

Answer 1

[Teja Muppirala]

"The only way i come to think of would be to change the NaN-values to 1"

That sounds like a reasonable idea to me:

X = [2 3 4; nan 2 7; 2 5 nan]
Y = X;
Y(isnan(Y)) = 1;
prod(Y)

[Anna]

Thank you for your help, I'd better do it like that then :)

[Jerry Gregoire]

Jonas had a good entry dealing with this issue and why you may want to consider the implications of doing this.

http://stackoverflow.com/questions/14178843/matlab-matrix-multiplication-ignoring-nans

Answer 2

[Steven Lord]

If you're using release R2017a or later, use the 'omitnan' flag in your call to prod.