HOW TO USE RANDOM and Cross paired?

there are two conditions

(1) K1 + K2 + K3 =1

(2) K1 > K2 > K3

I need 100 random combinations of the K1, K2 and K3

0<Ki's<1, all Ki's must satisfy both the conditions

the question above, I already got the answer. But if anyone has others idea, please comment below.

_The old answer:

N = 100 ;

k = linspace(0,1,N) ;

[K1,K2,K3] = ndgrid(k,k,k) ;

thesum = K1+K2+K3 ;

idx = thesum==1 ;

K1 = K1(idx) ; K2 = K2(idx) ; K3 = K3(idx) ;

K = [K1 K2 K3] ;

idx = K1<K2 & K2<K3 ;

iwant = K(idx,:) ;_

*Now, here is the new question:

If I want to declare K1 = 0.5? how to generate K2 and K3?*

Answer 1

[Thorsten]

K2 = 0.5*rand(100, 1);
K2(K2 < 0.25) = 0.25 + K2(K2 < 0.25);

iwant = [0.5*ones(100, 1), K2, 0.5 - K2];

[Kaiser]

I can't understand you. Can you please write the complete answer to me?

Answer 2

[Roger Stafford]

Use my randfixedsum in the File Exchange at:

http://www.mathworks.com/matlabcentral/fileexchange/9700-random-vectors-with-fixed-sum

K = sort(randfixedsum(3,100,1,0,1),1,’descend’);