How can I filter the negative value?

Hello, I am a beginner at MATLAB and English, but I would like to use this tool, please give a answer.

the matrix A like below:

A = [100 -20 50 -3]

I would like to convert like below:

B = [100 0 50 0] %make 0 if a value is negative.

or

C = [10000 -20 5000 -3] % multiply 100 if value is positive.

how can I do this convertion?

Answer 1

[Rick Rosson]

   B = A.*(A>0);
   C = A.*(A>0)*100 + A.*(A<0);

[sewook]

Thank you~ ^^;

it is very simple and clear~~