1. A storage medium storing instructions executable to implement a sum-of-exponentials function optimization method including the operations of: constructing an upper bound using a double majorization bounding process to a sum-of-exponentials function including at least one summation of exponentials; optimizing the constructed upper bound respective to parameters of the exponentials of the at least one summation of exponentials to generate optimized parameters; and outputting the optimized sum-of-exponentials function represented at least by the optimized parameters.