I have come across a difference between APL and J in matrix divide. I went on the J Forum and see that there has been some discussion on this but couldnt see the answer to my question (which I might have missed). I have two situations. In the first case, my left and right arguments to matrix divide are:
Larg 0.204761 0.164397 0.157506 0.157351 0.15296 0.143288 0.12958 0.113711 0.0972323 0.0813807 0.0668824 and Rarg 0.273501 33.6993 _15.6811 0.505944 50.5733 _10.6639 0.700719 52.4143 _6.45982 0.796474 47.0372 _4.393 0.861592 39.7353 _2.98746 0.905876 32.2908 _2.03162 0.935991 25.5423 _1.38161 0.95647 19.8067 _0.939561 0.970398 15.1266 _0.638949 0.979869 11.4137 _0.434517 0.98631 8.52817 _0.295493 Larg %. Rarg gives me 0.0763215 0.00125631 _0.008049 which is what Domino in APL III ver 1.2 estimates as well. I am writing code to estimate parameter bias when some of the parameters are conditionally linear. In this second situation, the two arguments are Larg 0.0387946 0.0263726 0.0159726 0.0108677 0.00739584 0.00503257 0.00340808 0.00233151 0.00157923 0.00107516 0.000729004 And Rarg (same matrix as above) 0.273501 33.6993 _15.6811 0.505944 50.5733 _10.6639 0.700719 52.4143 _6.45982 0.796474 47.0372 _4.393 0.861592 39.7353 _2.98746 0.905876 32.2908 _2.03162 0.935991 25.5423 _1.38161 0.95647 19.8067 _0.939561 0.970398 15.1266 _0.638949 0.979869 11.4137 _0.434517 0.98631 8.52817 _0.295493 Here Larg %. Rarg gives me 0.000002152066984 _0.000000087245596 _0.002473889682694 While APLs Domino gives me ¯0.000007023400888 2.333431673E¯7 ¯0.002473197439 It could be that the Rarg matrix in the second situation is close to singular and that both languages are giving non-sensical results but I am not sure. Could anyone explain the difference between what %. And Domino are doing? Thanks Bob ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
