Matlab if loop function, How to improve this function? -

i new matlab , trying figure how write following function in smart/efficient way.

first create matrix y entries hl, , every line permutation of predefined length n.

for example, n=3 first line of matrix y : h h h. want each line, create matrix of size n x n example entry (1,2) corresponds variable links entry y(1,1) y(1,2) , , entry y(3,2) corresponds variable links entry y(1,3) y(1,2). possible?

function a1=mystupidfunction(s , n) %n number of agents , s number of state, function %returns matrix of influence. stupid code must improved work %n agents  x = 'hl';                 %// set of possible types k = n;                      %// length of each permutation  %// create possible permutations (with repetition) of letters stored in x c = cell(k, 1);             %// preallocate cell array [c{:}] = ndgrid(x); y = cellfun(@(x){x(:)}, c); y = [y{:}];  a1 = sym('a1',[n n], 'positive' ); syms h l a_hh a_hl a_lh a_ll k=s     i=1:n         j=1:n             if ( y(k,1)==h) && ( y(k,2)==h) && (y(k,3)==h)                 a1(i,j)=a_hh             elseif ( y(k,1)==l) && ( y(k,2)==l) && (y(k,3)==l)                 a1(i,j)=a_ll             elseif ( y(k,1)==h) && ( y(k,2)==l) && (y(k,3)==l)                 a1(1,1)=a_hh                 a1(1,2)=a_hl                 a1(1,3)=a_hl                 a1(2,1)=a_lh                 a1(3,1)=a_lh                 a1(2,2)=a_ll                 a1(2,3)=a_ll                 a1(3,3)=a_ll                 a1(3,2)=a_ll             elseif ( y(k,1)==h) && ( y(k,2)==h) && (y(k,3)==l)                 a1(1,1)=a_hh                 a1(1,2)=a_hh                 a1(1,3)=a_hl                 a1(2,1)=a_hh                 a1(3,1)=a_lh                 a1(2,2)=a_hh                 a1(2,3)=a_hl                 a1(3,3)=a_ll                 a1(3,2)=a_lh             elseif ( y(k,1)==l) && ( y(k,2)==l) && (y(k,3)==h)                 a1(1,1)=a_ll                 a1(1,2)=a_ll                 a1(1,3)=a_lh                 a1(2,1)=a_ll                 a1(3,1)=a_lh                 a1(2,2)=a_ll                 a1(2,3)=a_lh                 a1(3,3)=a_hh                 a1(3,2)=a_hl             elseif ( y(k,1)==l) && ( y(k,2)==h) && (y(k,3)==h)                 a1(1,1)=a_ll                 a1(1,2)=a_lh                 a1(1,3)=a_lh                 a1(2,1)=a_hl                 a1(3,1)=a_hl                 a1(2,2)=a_hh                 a1(2,3)=a_hh                 a1(3,3)=a_hh                 a1(3,2)=a_hh             elseif ( y(k,1)==l) && ( y(k,2)==h) && (y(k,3)==l)                 a1(1,1)=a_ll                 a1(1,2)=a_lh                 a1(1,3)=a_ll                 a1(2,1)=a_hl                 a1(3,1)=a_ll                 a1(2,2)=a_hh                 a1(2,3)=a_hl                 a1(3,3)=a_ll                 a1(3,2)=a_lh              elseif ( y(k,1)==h) && ( y(k,2)==l) && (y(k,3)==h)                 a1(1,1)=a_hh                 a1(1,2)=a_hl                 a1(1,3)=a_hh                 a1(2,1)=a_lh                 a1(3,1)=a_hh                 a1(2,2)=a_ll                 a1(2,3)=a_hl                 a1(3,3)=a_hh                 a1(3,2)=a_hl             else a(i,j)=0             end         end     end end 

for example when n=3 , s=1, function returns:

a =  [ a_hh, a_hh, a_hh] [ a_hh, a_hh, a_hh] [ a_hh, a_hh, a_hh] 

notes:

c = cell(k, 1);             %// preallocate cell array [c{:}] = ndgrid(x);         %// create k grids of values y = cellfun(@(x){x(:)}, c); %// convert grids column vectors y = [y{:}]; 

the output n=3 : y =

hhh lhh hlh llh hhl lhl hll lll 

s scalar indicates number of line in matrix y (which corresponds "state")

if have 2 states h , l, said in comment use 0 , 1, binary logic.

to y combinations, count in binary until have right number of digit , convert each bit state decide:

so order n=3 have:

n = 3 ; = de2bi( (0:2^n-1).' ) 

which gives 3 digits binary combinations:

a =      0     0     0      1     0     0      0     1     0      1     1     0      0     0     1      1     0     1      0     1     1      1     1     1 

if want them in ascii format, can convert them:

b = char( ones(size(a))* 'l') ; b(~a) = 'h' ; 

to obtain:

b = hhh lhh hlh llh hhl lhl hll lll 

so if want keep "ascii" character logic (and output), job:

function out = combiadjacent( k , n )  yb = de2bi( (0:2^n-1).' ) ;      %'// combinations y = char( ones(size(yb))* 'l') ; y(~yb) = 'h' ;  = char( zeros(n,2*n) ) ; col=1:n     acol = [col col+1] + (col-1) ;     a(:,acol)   = [y(k,col)*ones(n,1)  y(k,:).'] ; end  out = reshape( cellstr( reshape(a.',2,[]).' ) , n , n ).' ; 

will give cell array output like:

>> = combiadjacent( 4 , 3 ) =      'll'    'll'    'hl'     'll'    'll'    'hl'     'lh'    'lh'    'hh' 

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however, if not picky exact output format, solution below run faster:

function out = combiadjacent( k , n )  y = de2bi( (0:2^n-1).' ) ;         %'// combinations  b = ones(n,1)*y(k,:) ;   %// use cell array of characters out = cellfun( @(a,b) char(cat(2,a+65,b+65)) , num2cell(b) ,num2cell(b.'),'uni',0) ;  %'// or use cell array of double in output (even faster) %// out = cellfun( @(a,b) cat(2,a,b) , num2cell(b) ,num2cell(b.'),'uni',0)  %// or cell array of boolean %// out = cellfun( @(a,b) logical(cat(2,a,b)) , num2cell(b) ,num2cell(b.'),'uni',0) ; 

which give you

>> = combiadjacent( 4 , 3 ) =      'bb'    'bb'    'ab'     'bb'    'bb'    'ab'     'ba'    'ba'    'aa' 

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note: whatever solution choose, prudent add checking condition k make sure user not request line doesn't exist.