convert/mathorner writes the polynomial poly in the variable var in horner or ``nested'' form. var may be the name of a matrix, an unnamed matrix, or just an unassigned name.

If there is only one indeterminate in poly then it is not necessary to specify the third argument var. In the case where poly is a polynomial in an unnamed matrix the third argument is required.

Horner form allows you to evaluate polynomials of matrices in the most efficient manner. For a polynomial of degree n there will be n adds and n multiplications needed to evaluate the Horner form.