A machine learning apparatus determines an order in which numerical values in an input dataset are to be entered to a neural network for data classification, based on a reference pattern that includes an array of reference values to provide a criterion for ordering the numerical values. The machine learning apparatus then calculates an output value of the neural network whose input-layer neural units respectively receive the numerical values arranged in the determined order. The machine learning apparatus further calculates an input error at the input-layer neural units, based on a difference between the calculated output value and a correct classification result indicated by a training label. The machine learning apparatus updates the reference values in the reference pattern, based on the input error at the input-layer neural units.
Please help me write a proper abstract based on the patent claims. CLAIM: 1. A non-transitory computer-readable storage medium storing a learning program that causes a computer to perform a procedure comprising: obtaining an input dataset including a set of numerical values and a training label indicating a correct classification result corresponding to the input dataset; determining an input order in which the numerical values in the input dataset are to be entered to a neural network for data classification, based on a reference pattern that includes an array of reference values to provide a criterion for ordering the numerical values; calculating an output value of the neural network whose input-layer neural units respectively receive the numerical values arranged in the input order; calculating an input error at the input-layer neural units of the neural network, based on a difference between the calculated output value and the correct classification result indicated by the training label; and updating the reference values in the reference pattern, based on the input error at the input-layer neural units. 2. The non-transitory computer-readable storage medium according to claim 1, wherein the determining of an input order includes: forming a first vector whose elements are the numerical values arranged in a specific order; forming a second vector whose elements are the reference values in the reference pattern; and seeking an input order of the numerical values that maximizes an inner product of the first vector and the second vector, by varying the specific order. 3. The non-transitory computer-readable storage medium according to claim 1, wherein the updating of the reference values includes: selecting one of the reference values in the reference pattern; determining a tentative input order of the numerical values, based on a temporary reference pattern generated by temporarily varying the selected reference value by a specified amount; calculating difference values between the numerical values arranged in the input order determined by using the reference pattern and corresponding numerical values arranged in the tentative input order determined by using the temporary reference pattern; determining whether to increase or decrease the selected reference value in the reference pattern, based on the input error and the difference values; and modifying the selected reference value in the reference pattern according to a result of the determining of whether to increase or decrease. 4. The non-transitory computer-readable storage medium according to claim 3, wherein the determining of whether to increase or decrease the selected reference value includes: forming a third vector representing the input error at the input-layer neural units; forming a fourth vector from the difference values arranged according to the tentative input order of the numerical values; and determining whether to increase or decrease the selected reference value, based on an inner product of the third vector and the fourth vector. 5. A machine learning method comprising: obtaining an input dataset including a set of numerical values and a training label indicating a correct classification result corresponding to the input dataset; determining, by a processor, an input order in which the numerical values in the input dataset are to be entered to a neural network for data classification, based on a reference pattern that includes an array of reference values to provide a criterion for ordering the numerical values; calculating, by the processor, an output value of the neural network whose input-layer neural units respectively receive the numerical values arranged in the input order; calculating, by the processor, an input error at the input-layer neural units of the neural network, based on a difference between the calculated output value and the correct classification result indicated by the training label; and updating, by the processor, the reference values in the reference pattern, based on the input error at the input-layer neural units. 6. A machine learning apparatus comprising: a memory that stores therein a reference pattern including an array of reference values to provide a criterion for ordering numerical values to be entered to a neural network for data classification; and a processor configured to perform a procedure including: obtaining an input dataset including a set of numerical values and a training label indicating a correct classification result corresponding to the input dataset; determining an input order in which the numerical values in the input dataset are to be entered to the neural network, based on the reference pattern in the memory; calculating an output value of the neural network whose input-layer neural units respectively receive the numerical values arranged in the input order; calculating an input error at the input-layer neural units of the neural network, based on a difference between the calculated output value and the correct classification result indicated by the training label; and updating the reference values in the reference pattern, based on the input error at the input-layer neural units.