How to extract non-consecutive submatrix in a easier way

Hi, everyone,

If I have a 100 by 100 matrix and I want to extract its 10 to 20, 40 to 50 and 70 to 80 rows and columns,

Is there a easier way rather than submatrix the rows first and then the columns and use stack or augment to assemble the submatrice?

Such as define a index of the rows and columns I want to extract and then extract the index from the matrix in Matlab?

E.g, index= [10:20 40:50 70:80]

K_BC=K(index, index)

Best

Shawn