step(H,X) writes one frame of data, X , to the variable stored in the MAT file. The variable is assumed to be N-dimensional and a MATLAB built-in data type. If the FrameBasedProcessing property is true, the data is written to the file by concatenating along the first dimension. If FrameBasedProcessing is false, the data is written by appending an additional dimension to the end of the data set.
Note: The object performs an initialization the first time the step method is executed. This initialization locks nontunable properties and input specifications, such as dimensions, complexity, and data type of the input data. If you change a nontunable property or an input specification, the System object™ issues an error. To change nontunable properties or inputs, you must first call the release method to unlock the object.