vector not produced missing some '.' ?

조회 수: 1(최근 30일)
john birt
john birt 2011년 4월 7일
something is wrong with this code
t=0:0.1:1;
g = (0.30/(2*(pi*t^3)^0.5))*exp((-0.30^2)/(4*t));
As the vector g never gets made, I'm sure I need to put some '.' somewhere but I really don't understand this whole '.' stuff
  댓글 수: 1
Paulo Silva
Paulo Silva 2011년 4월 7일
Sean answer is great for such cases, also when there's one dot missing matlab tells you what's the operation in the error message:
mtimes % before *
mdivide % before /
mpower % before ^

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채택된 답변

Paulo Silva
Paulo Silva 2011년 4월 7일
t=0:0.1:1;
g = (0.30./(2*(pi*t.^3).^0.5)).*exp((-0.30^2)./(4*t));

추가 답변(3개)

Sean de Wolski
Sean de Wolski 2011년 4월 7일
vectorize('g = (0.30/(2*(pi*t^3)^0.5))*exp((-0.30^2)/(4*t))');
A brainless way for us lazies.
  댓글 수: 4
Sean de Wolski
Sean de Wolski 2011년 4월 7일
Eval, is the king of MATLAB laziness!

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Matt Fig
Matt Fig 2011년 4월 7일
As a general rule when dealing with operations on arrays, use a dot before every one of the three operators:
* / ^
If you do this you will be fine.
  댓글 수: 1
Sean de Wolski
Sean de Wolski 2011년 4월 7일
and \

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David Young
David Young 2011년 4월 7일
If you don't understand the operators, the most straighforward thing is to use
g = (0.30 ./ (2 .* (pi .* t .^ 3) .^ 0.5)) .* exp((-0.30 .^ 2) ./ (4 .* t));
so that all the operators behave as elementwise operators (which I guess is what you want). If you understand the difference, you can omit some of the dots, but they do no harm.
It's not all that hard really: *, / and ^ carry out matrix operations (like matrix multiplication, as defined here), while .*, ./ and .^ operate point by point on the elements of the matrices.

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