ATAN2 ATAN2 Inverse Trigonometric 4-Quadrant Arctangent Function Usage Computes the atan2 function for its argument. The general syntax for its use is y = atan2(y,x) where x and y are n-dimensional arrays of numerical type. Integer types are promoted to the double type prior to calculation of the atan2 function. The size of the output depends on the size of x and y. If x is a scalar, then z is the same size as y, and if y is a scalar, then z is the same size as x. The type of the output is equal to the type of |y/x|.