matrix issue with null
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Hello, i have this code in mathematica and i want to do it in matlab:
T = Table[{Null, Null}, {Maxstep}]
t = Table[Null, {Maxstep}]
T2 = Table[{0, 0}, {Maxstep}]
How can i do it?(the null?) Thanks!
EDIT---->> Also,this : ml = Table[If[RandomReal[] < 0.5, 1, -1], {L}, {L}];
I tried this: ml=rand(L,L); if rand()<0.5 ml(:,:)==1 else ml(:,:)==-1 end ml
but it gives me random numbers 0-1 and i want only 1 and -1
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채택된 답변
Matt Tearle
2011년 2월 19일
If you want a 2-by-|Maxstep| table of nulls, you can do
T = NaN(2,Maxstep);
This way, T will be numeric. Otherwise, go with Matt Fig's suggestion of a cell array of empty arrays.
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Matt Tearle
2011년 2월 20일
If you want the sum of everything, you can reshape into a 1-D array. A neat short-cut syntax for this is sum(matrix(:))
추가 답변 (2개)
Matt Tearle
2011년 2월 19일
Best practice is to make separate posts for separate questions. For the first question, can you explain what the desired output is? (I haven't used Mma in ages)
For the second question, your approach wasn't bad, but your if condition invoked rand a second time, then set all of ml to 1 or -1. Try rounding, in conjunction with shifting and scaling:
ml = 2*round(rand(L,L)) - 1;
Matt Fig
2011년 2월 19일
Since I don't have Mathematica, and many may not, can you show what the output of those commands is? That way we could try to match it in MATLAB. My best guess is you want something like this:
T = cell(1,Maxstep);
ml = rand(L,L);
ml(ml>.5) = 1;
ml(ml<=.5) = -1
Or all at once:
ml = round(rand(L,L))*2-1
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