Re: [Phys-L] From a Math Prof (physics BS major) at my institution ( math challenge)

[Jeffrey Schnick <JSchnick@Anselm.Edu>]

> -----Original Message-----
> From: Phys-l [mailto:phys-l-bounces@phys-l.org] On Behalf Of brian
> whatcott
> Sent: Wednesday, February 26, 2014 12:41 PM
> To: phys-l@phys-l.org
> Subject: Re: [Phys-L] From a Math Prof (physics BS major) at my institution (
> math challenge)
>
> If the intention is to draw five integers in the range 1..35 from a hat, what do
> you do if you draw a number that's already drawn?
...
I think what Paul is saying is that after you pick a number you shouldn't put it back in the hat before having picked all five.  I can't see how it could matter but I have created a new version of the code, one that uses all values returned by the pseudo-random distribution generator and it is running now with n = a million.  I have pasted it below.  See any mistakes in it?  If not, what is your prediction on how the results will compare with those of the old code?

function dummy = getdist2(n)
    tic
    for m=1:n
        a=zeros(21,5);
        for i=1:21
            numsLeft=0:36;
            for j = 1:5
                nIndex = fix(2+rand*(36-j));
                a(i,j)=numsLeft(nIndex);
                numsLeft=[numsLeft(1:nIndex-1),numsLeft(nIndex+1:38-j)];
            end
        end
        a=sort(a,2);
        nrounds(m)=sum(10==a(:)) + sum(20==a(:)) + sum(30==a(:));
        nseq2(m)=0;
        for i=1:21
            b=diff(a(i,:));
            nseq2(m)=nseq2(m)+sum(1==b);
        end
        
    end


    for i=0:6
        totalrounds(i+1)=sum(i==nrounds);
    end
    totalrounds=totalrounds
    
    for i=0:6
        totalseq2(i+1)=sum(i==nseq2);
    end
    totalseq2=totalseq2
    
    for i=0:6
        total(i+1)= sum( nseq2<=i & nrounds<=i );
    end
    total=total
    
    toc
end