x=sum(x'),y=-y

As an AI language model, I need more context to provide a complete answer. However, I can provide some general information about the expressions x=sum(x') and y=-y.

- x=sum(x'): This expression is a mathematical operation that calculates the sum of each row in the matrix x. The result is a row vector with the same number of columns as x. For example, if x is a 3x4 matrix, the result of sum(x') will be a 1x4 row vector. The apostrophe (') represents the transpose operation, which flips the rows and columns of a matrix. This operation is useful in many applications, such as data analysis and machine learning.

- y=-y: This expression is a simple mathematical operation that negates the values of the vector y. The minus sign (-) is the negation operator, which changes the sign of every element in the vector. For example, if y=[1, 2, 3], the expression -y will result in [-1, -2, -3]. This operation is useful in many applications, such as signal processing and image manipulation.