The determinant is traditionally defined only for square matrices, as it relates to the change in volume due to basis transformations. However, some discussions suggest methods for finding generalized determinants for non-square matrices, referencing a specific paper that explores identities related to this concept. To compute a generalized determinant for a 3x15 matrix, one approach involves calculating the determinants of all 3x3 submatrices and applying an alternating sum based on the signs determined by the column indices. The conversation highlights the need for further resources or techniques to clarify these methods. Understanding these generalized determinants may have applications in fields like image processing.