Nonnegative rank is a way to describe certain types of matrices using other matrices that have nonnegative numbers in them. It's like putting together a puzzle: you have a big puzzle piece, which is the original matrix, and you're trying to find smaller puzzle pieces that fit together and can be used to represent the original puzzle piece.
These smaller puzzle pieces are the nonnegative rank matrices. They're made up of nonnegative numbers, which means they're either zero or positive, and they can be used to represent the original matrix in a certain way.
Now, let's talk about why we would want to do this. Nonnegative rank can help us understand the structure and properties of matrices, and it's often used in things like data analysis and machine learning. By breaking a matrix down into nonnegative rank matrices, we can gain insights into the patterns and relationships that exist within the data.
So, to summarize: nonnegative rank is a way to represent matrices using smaller matrices that have nonnegative numbers in them. This helps us understand the structure and properties of matrices, and can be useful in analyzing large datasets.