Delete Rows that have a negative number in their first column.

Hi, I have a 5x2 matrix like this:

A=[-1 2;2 -4;-5 9;-3 7;8 6;]

Now I want a code to delete rows that have negative value in their first column. so the output will be this matrix: newA=[2 -4;8 6;]

tnx.

Answer 1

[Paulo Silva]

A=[-1 2;2 -4;-5 9;-3 7;8 6]
%find the rows that we don't want, remove them and show the rest  
A(A(:,1)<0,:)=[]

another way

A(A(:,1)>=0,:)     %find and show only the rows that we want

Answer 2

[Fangjun Jiang]

A=[-1 2;2 -4;-5 9;-3 7;8 6;]
Index=A(:,1)<0;
NewA=A(~Index,:)

Or, a one-liner:

A=[-1 2;2 -4;-5 9;-3 7;8 6;]
A(A(:,1)<0,:)=[]

Answer 3

[Hajik zagori]

Thanks Paulo and Fangjun. :X Both of your answers worked perfectly.