HP Forum Archive 17

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Is there a command to total all matrix elements? Message #1 Posted by Reuben on 23 Feb 2007, 8:54 p.m. I've got a 5x6 matrix and I need to add all the elements together. I didn't want to have to decompile the matrix and perform '+' 29 times though. I've looked in the matrix section in the user guide a few times, and can't find anything that will do this. Thanks in advance! --Reuben

Re: Is there a command to total all matrix elements? Message #2 Posted by allen on 23 Feb 2007, 11:24 p.m., in response to message #1 by Reuben (Revised from earlier post) You could just take the dot product with unity matrix: [[ 1 2 3 ] [[1 1 1] [ 4 5 6 ] dot [1 1 1] = 45 [ 7 8 9 ]] [1 1 1]] which is 1+2+3+4+5+6+7+8+9=45 Edited: 24 Feb 2007, 10:19 a.m.

Re: Is there a command to total all matrix elements? Message #3 Posted by John Keith on 25 Feb 2007, 7:49 p.m., in response to message #2 by allen A little longer but faster: OBJ-> OBJ-> DROP * ->LIST \Sigma\LIST John

Re: Is there a command to total all matrix elements? Message #4 Posted by allen on 26 Feb 2007, 8:25 p.m., in response to message #3 by John Keith John, Right you are, your method is at least twice as fast as the method I posted above. My original response was much closer to your objobj method, but I revised it because it did not address the question. Reuben's question had "opportunities for learning" in programming (trying to sum a list by +,+,+,+,+,+,+) and in mathematics (not knowing that the DOT product already does sum the elements in a vector/matrix). So I thought it more fitting to address only the mathematics issue, hoping that he would take some initiave and figure out the rest. (e.g. a simpler, faster, better... way) Edited: 26 Feb 2007, 11:49 p.m.

<<DUP SIZE 1 CON DOT>> AKA soup in a Vietnamese Restraunt Message #5 Posted by allen on 25 Feb 2007, 12:28 a.m., in response to message #1 by Reuben << DUP SIZE 1 CON DOT >> (If you say it outloud to yourself it sounds very much like ordering soup in a Vietnamese Restraunt!) :-) Edited: 25 Feb 2007, 12:32 a.m.

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