NB. J Phrases Section 9A. Matrix Algebra

m0=: I=: =@i.@#                 NB. Identity matrix of order of y
m1=: inv=: %.                   NB. Matrix inverse
d2=: mq=: %.                    NB. Matrix quotient
d3=: mp=: +/ . *                NB. Matrix product
d4=: amp=: -/ . *               NB. Alternating matrix product
m5=: det=: -/ . *               NB. Determinant
d6=: fit=: {:@] %. {.@] ^/ i.@[ NB. d fit x,:f x is coeffs of pn fit of degree d-1
