function _create(data, format, datatype) {
    // get storage format constructor
    var M = type.Matrix.storage(format || 'default'); // create instance

    return new M(data, datatype);
  }
Create a new Matrix with given storage format
@param {Array} data
@param {string} [format]
@param {string} [datatype]
@returns {Matrix} Returns a new Matrix
@private