/ NetNews Offline 2 / NetNews Offline Volume 2.iso / news / comp / lang / c++-part2 / 16052

< prev

next >

MacOS 8.1

Win98

DOS

browse contents

view JSON data

view as text

+--------+-------------------------+-------------------------+--------+--------+
|00000000| 50 61 74 68 3a 20 73 75 | 6c 6c 69 76 61 6e 2e 75 |Path: su|llivan.u|
|00000010| 63 63 2e 68 75 6c 6c 2e | 61 63 2e 75 6b 21 6e 65 |cc.hull.|ac.uk!ne|
|00000020| 77 73 6d 61 73 74 65 72 | 40 68 75 6c 6c 2e 61 63 |wsmaster|@hull.ac|
|00000030| 2e 75 6b 0a 46 72 6f 6d | 3a 20 22 4a 2e 44 2e 48 |.uk.From|: "J.D.H|
|00000040| 6f 79 6c 61 6e 64 22 20 | 3c 4a 2e 44 2e 48 6f 79 |oyland" |<J.D.Hoy|
|00000050| 6c 61 6e 64 40 61 70 70 | 68 79 73 2e 68 75 6c 6c |land@app|hys.hull|
|00000060| 2e 61 63 2e 75 6b 3e 0a | 4e 65 77 73 67 72 6f 75 |.ac.uk>.|Newsgrou|
|00000070| 70 73 3a 20 63 6f 6d 70 | 2e 6c 61 6e 67 2e 63 2b |ps: comp|.lang.c+|
|00000080| 2b 0a 53 75 62 6a 65 63 | 74 3a 20 52 65 3a 20 4f |+.Subjec|t: Re: O|
|00000090| 76 65 72 69 64 69 6e 67 | 20 5b 5d 20 66 6f 72 20 |veriding| [] for |
|000000a0| 43 2b 2b 20 6d 61 74 72 | 69 78 20 63 6c 61 73 73 |C++ matr|ix class|
|000000b0| 0a 44 61 74 65 3a 20 39 | 20 41 70 72 20 31 39 39 |.Date: 9| Apr 199|
|000000c0| 36 20 30 39 3a 34 39 3a | 35 30 20 47 4d 54 0a 4f |6 09:49:|50 GMT.O|
|000000d0| 72 67 61 6e 69 7a 61 74 | 69 6f 6e 3a 20 55 6e 69 |rganizat|ion: Uni|
|000000e0| 76 65 72 73 69 74 79 20 | 6f 66 20 48 75 6c 6c 0a |versity |of Hull.|
|000000f0| 4d 65 73 73 61 67 65 2d | 49 44 3a 20 3c 34 6b 64 |Message-|ID: <4kd|
|00000100| 62 72 75 24 35 69 32 40 | 73 75 6c 6c 69 76 61 6e |bru$5i2@|sullivan|
|00000110| 2e 75 63 63 2e 68 75 6c | 6c 2e 61 63 2e 75 6b 3e |.ucc.hul|l.ac.uk>|
|00000120| 0a 52 65 66 65 72 65 6e | 63 65 73 3a 20 3c 34 6a |.Referen|ces: <4j|
|00000130| 75 36 76 66 24 6b 6f 70 | 40 6e 65 77 73 2e 69 61 |u6vf$kop|@news.ia|
|00000140| 73 74 61 74 65 2e 65 64 | 75 3e 0a 4e 4e 54 50 2d |state.ed|u>.NNTP-|
|00000150| 50 6f 73 74 69 6e 67 2d | 48 6f 73 74 3a 20 68 75 |Posting-|Host: hu|
|00000160| 73 74 6f 6e 2e 68 75 6c | 6c 2e 61 63 2e 75 6b 0a |ston.hul|l.ac.uk.|
|00000170| 4d 69 6d 65 2d 56 65 72 | 73 69 6f 6e 3a 20 31 2e |Mime-Ver|sion: 1.|
|00000180| 30 0a 43 6f 6e 74 65 6e | 74 2d 54 79 70 65 3a 20 |0.Conten|t-Type: |
|00000190| 74 65 78 74 2f 70 6c 61 | 69 6e 3b 20 63 68 61 72 |text/pla|in; char|
|000001a0| 73 65 74 3d 75 73 2d 61 | 73 63 69 69 0a 43 6f 6e |set=us-a|scii.Con|
|000001b0| 74 65 6e 74 2d 54 72 61 | 6e 73 66 65 72 2d 45 6e |tent-Tra|nsfer-En|
|000001c0| 63 6f 64 69 6e 67 3a 20 | 37 62 69 74 0a 58 2d 4d |coding: |7bit.X-M|
|000001d0| 61 69 6c 65 72 3a 20 4d | 6f 7a 69 6c 6c 61 20 31 |ailer: M|ozilla 1|
|000001e0| 2e 31 4e 20 28 58 31 31 | 3b 20 49 3b 20 53 75 6e |.1N (X11|; I; Sun|
|000001f0| 4f 53 20 34 2e 31 2e 33 | 43 20 73 75 6e 34 6d 29 |OS 4.1.3|C sun4m)|
|00000200| 0a 54 6f 3a 20 6d 6c 72 | 69 76 61 73 40 69 61 73 |.To: mlr|ivas@ias|
|00000210| 74 61 74 65 2e 65 64 75 | 0a 58 2d 55 52 4c 3a 20 |tate.edu|.X-URL: |
|00000220| 6e 65 77 73 3a 34 6a 75 | 36 76 66 24 6b 6f 70 40 |news:4ju|6vf$kop@|
|00000230| 6e 65 77 73 2e 69 61 73 | 74 61 74 65 2e 65 64 75 |news.ias|tate.edu|
|00000240| 0a 0a 6d 6c 72 69 76 61 | 73 40 69 61 73 74 61 74 |..mlriva|s@iastat|
|00000250| 65 2e 65 64 75 20 28 4d | 61 74 74 68 65 77 20 4c |e.edu (M|atthew L|
|00000260| 20 52 69 76 61 73 29 20 | 77 72 6f 74 65 3a 0a 3e | Rivas) |wrote:.>|
|00000270| 0a 3e 49 27 6d 20 61 74 | 74 65 6d 70 74 69 6e 67 |.>I'm at|tempting|
|00000280| 20 74 6f 20 77 72 69 74 | 65 20 61 20 73 69 6d 70 | to writ|e a simp|
|00000290| 6c 65 20 6d 61 74 72 69 | 78 20 63 6c 61 73 73 20 |le matri|x class |
|000002a0| 77 68 69 63 68 20 77 69 | 6c 6c 0a 3e 61 6c 6c 6f |which wi|ll.>allo|
|000002b0| 77 20 6d 65 20 74 6f 20 | 75 73 65 20 74 68 65 20 |w me to |use the |
|000002c0| 60 5b 5d 27 20 74 6f 20 | 61 63 63 65 73 73 20 74 |`[]' to |access t|
|000002d0| 68 65 20 6d 61 74 72 69 | 78 20 63 6f 65 66 66 69 |he matri|x coeffi|
|000002e0| 63 69 65 6e 74 73 2e 0a | 3e 54 68 65 20 6d 65 74 |cients..|>The met|
|000002f0| 68 6f 64 20 49 20 75 73 | 65 20 69 73 20 74 68 65 |hod I us|e is the|
|00000300| 20 66 6f 6c 6c 77 69 6e | 67 3a 0a 3e 0a 3e 09 76 | follwin|g:.>.>.v|
|00000310| 69 72 74 75 61 6c 20 64 | 6f 75 62 6c 65 20 2a 20 |irtual d|ouble * |
|00000320| 6f 70 65 72 61 74 6f 72 | 5b 5d 28 73 68 6f 72 74 |operator|[](short|
|00000330| 20 72 29 20 7b 72 65 74 | 75 72 6e 20 63 6f 65 66 | r) {ret|urn coef|
|00000340| 5b 72 5d 3b 7d 0a 3e 0a | 3e 77 68 69 63 68 20 49 |[r];}.>.|>which I|
|00000350| 20 66 6f 75 6e 64 20 69 | 6e 20 61 20 62 6f 6f 6b | found i|n a book|
|00000360| 2e 20 49 20 64 65 72 69 | 76 65 64 20 61 20 73 79 |. I deri|ved a sy|
|00000370| 6d 6d 65 74 72 69 63 20 | 6d 61 74 72 69 78 20 63 |mmetric |matrix c|
|00000380| 6c 61 73 73 0a 3e 66 72 | 6f 6d 20 74 68 69 73 20 |lass.>fr|om this |
|00000390| 62 61 73 65 2e 20 49 6e | 20 74 68 65 20 73 79 6d |base. In| the sym|
|000003a0| 6d 65 74 72 69 63 20 63 | 6c 61 73 73 2c 20 49 20 |metric c|lass, I |
|000003b0| 6f 6e 6c 79 20 73 74 6f | 72 65 20 74 68 65 0a 3e |only sto|re the.>|
|000003c0| 75 70 70 65 72 20 74 72 | 69 61 6e 67 75 6c 61 72 |upper tr|iangular|
|000003d0| 20 63 6f 65 66 66 69 63 | 69 65 6e 74 73 20 74 6f | coeffic|ients to|
|000003e0| 20 73 61 76 65 20 6d 65 | 6d 6f 72 79 20 28 6d 79 | save me|mory (my|
|000003f0| 20 77 6f 72 6b 0a 3e 69 | 73 20 65 78 74 72 65 6d | work.>i|s extrem|
|00000400| 65 6d 6c 79 20 6d 65 6d | 6f 72 79 20 69 6e 74 65 |emly mem|ory inte|
|00000410| 6e 73 69 76 65 20 73 6f | 20 74 68 69 73 20 69 73 |nsive so| this is|
|00000420| 20 6e 65 63 65 73 73 61 | 72 79 29 2e 20 49 20 68 | necessa|ry). I h|
|00000430| 61 76 65 20 61 6e 0a 3e | 61 63 63 65 73 73 20 66 |ave an.>|access f|
|00000440| 75 6e 63 74 69 6f 6e 20 | 77 68 69 63 68 20 63 68 |unction |which ch|
|00000450| 65 63 6b 73 20 74 68 65 | 20 63 61 6c 6c 65 64 20 |ecks the| called |
|00000460| 66 6f 72 20 70 6f 73 69 | 74 69 6f 6e 20 61 6e 64 |for posi|tion and|
|00000470| 0a 3e 72 65 74 75 72 6e | 73 20 74 68 65 20 63 6f |.>return|s the co|
|00000480| 72 72 65 63 74 20 63 6f | 65 66 66 69 63 69 65 6e |rrect co|efficien|
|00000490| 74 2c 20 61 6e 64 20 69 | 74 20 6c 6f 6f 6b 73 20 |t, and i|t looks |
|000004a0| 6c 69 6b 65 3a 0a 3e 0a | 3e 09 64 6f 75 62 6c 65 |like:.>.|>.double|
|000004b0| 20 73 79 6d 6d 61 74 72 | 69 78 3a 3a 67 65 74 56 | symmatr|ix::getV|
|000004c0| 61 6c 75 65 28 73 68 6f | 72 74 20 69 2c 73 68 6f |alue(sho|rt i,sho|
|000004d0| 72 74 20 6a 29 0a 3e 09 | 7b 0a 3e 09 09 69 66 20 |rt j).>.|{.>..if |
|000004e0| 28 6a 20 3e 3d 20 69 29 | 20 72 65 74 75 72 6e 20 |(j >= i)| return |
|000004f0| 63 6f 65 66 66 5b 69 5d | 5b 6a 5d 3b 0a 3e 09 09 |coeff[i]|[j];.>..|
|00000500| 65 6c 73 65 20 72 65 74 | 75 72 6e 20 63 6f 65 66 |else ret|urn coef|
|00000510| 66 5b 6a 5d 5b 69 5d 3b | 0a 3e 09 7d 0a 3e 0a 3e |f[j][i];|.>.}.>.>|
|00000520| 49 20 77 6f 75 6c 64 20 | 6c 69 6b 65 20 74 6f 20 |I would |like to |
|00000530| 68 61 76 65 20 74 68 65 | 20 73 61 6d 65 20 61 63 |have the| same ac|
|00000540| 63 65 73 73 20 66 75 6e | 63 74 69 6f 6e 20 6d 65 |cess fun|ction me|
|00000550| 74 68 6f 64 2c 20 69 2e | 65 2e 2c 20 75 73 69 6e |thod, i.|e., usin|
|00000560| 67 20 60 5b 5d 27 2c 0a | 3e 66 6f 72 20 74 68 65 |g `[]',.|>for the|
|00000570| 20 73 79 6d 6d 65 74 72 | 69 63 20 63 6c 61 73 73 | symmetr|ic class|
|00000580| 20 61 73 20 77 65 6c 6c | 2e 0a 3e 0a 3e 49 20 68 | as well|..>.>I h|
|00000590| 61 76 65 20 74 77 6f 20 | 71 75 65 73 74 69 6f 6e |ave two |question|
|000005a0| 73 3a 0a 3e 0a 3e 20 20 | 31 29 20 49 73 20 74 68 |s:.>.>  |1) Is th|
|000005b0| 65 72 65 20 61 20 77 61 | 79 20 74 6f 20 75 73 65 |ere a wa|y to use|
|000005c0| 20 60 5b 5d 27 20 66 6f | 72 20 74 68 65 20 73 79 | `[]' fo|r the sy|
|000005d0| 6d 6d 65 74 72 69 63 20 | 63 6c 61 73 73 3f 0a 3e |mmetric |class?.>|
|000005e0| 0a 3e 20 20 32 29 20 48 | 6f 77 20 65 78 61 63 74 |.>  2) H|ow exact|
|000005f0| 6c 79 20 64 6f 65 73 20 | 74 68 65 20 66 69 72 73 |ly does |the firs|
|00000600| 74 20 72 6f 75 74 69 6e | 65 20 77 6f 72 6b 3f 20 |t routin|e work? |
|00000610| 49 27 76 65 20 6e 65 76 | 65 72 20 62 65 65 6e 20 |I've nev|er been |
|00000620| 73 75 72 65 0a 3e 20 20 | 20 20 20 61 6e 64 20 77 |sure.>  |   and w|
|00000630| 6f 75 6c 64 20 72 65 61 | 6c 6c 79 20 6c 69 6b 65 |ould rea|lly like|
|00000640| 20 74 6f 20 6b 6e 6f 77 | 2e 0a 3e 0a 3e 41 6e 79 | to know|..>.>Any|
|00000650| 20 68 65 6c 70 20 77 6f | 75 6c 64 20 62 65 20 61 | help wo|uld be a|
|00000660| 70 70 72 65 63 69 61 74 | 65 64 2e 20 49 20 64 6f |ppreciat|ed. I do|
|00000670| 20 6b 6e 6f 77 20 61 62 | 6f 75 74 20 6f 76 65 72 | know ab|out over|
|00000680| 6c 6f 61 64 69 6e 67 20 | 74 68 65 0a 3e 66 75 6e |loading |the.>fun|
|00000690| 63 74 69 6f 6e 20 63 61 | 6c 6c 69 6e 67 20 6f 70 |ction ca|lling op|
|000006a0| 65 72 61 74 6f 72 73 20 | 60 28 29 27 20 73 6f 20 |erators |`()' so |
|000006b0| 74 68 61 74 0a 3e 0a 3e | 09 4d 61 74 72 69 78 20 |that.>.>|.Matrix |
|000006c0| 41 28 6e 2c 6e 29 3b 0a | 3e 09 41 28 69 2c 6a 29 |A(n,n);.|>.A(i,j)|
|000006d0| 20 3d 20 31 2e 30 3b 0a | 3e 09 78 20 3d 20 41 28 | = 1.0;.|>.x = A(|
|000006e0| 69 2c 6a 29 3b 0a 3e 0a | 3e 77 68 69 63 68 20 69 |i,j);.>.|>which i|
|000006f0| 73 20 74 68 65 20 73 61 | 6d 65 20 61 73 20 74 68 |s the sa|me as th|
|00000700| 65 20 66 6f 72 74 72 61 | 6e 20 63 61 6c 6c 69 6e |e fortra|n callin|
|00000710| 67 20 63 6f 6e 76 65 6e | 74 69 6f 6e 2e 20 49 20 |g conven|tion. I |
|00000720| 64 6f 6e 27 74 20 72 65 | 61 6c 6c 79 0a 3e 77 61 |don't re|ally.>wa|
|00000730| 6e 74 20 74 6f 20 69 6d | 70 6c 65 6d 65 6e 74 20 |nt to im|plement |
|00000740| 69 74 20 74 68 69 73 20 | 77 61 79 20 61 6e 64 20 |it this |way and |
|00000750| 77 6f 75 6c 64 20 72 61 | 74 68 65 72 20 73 74 69 |would ra|ther sti|
|00000760| 63 6b 20 77 69 74 68 20 | 74 68 65 20 43 2b 2b 0a |ck with |the C++.|
|00000770| 3e 73 74 61 6e 64 61 72 | 64 20 69 66 20 49 20 63 |>standar|d if I c|
|00000780| 61 6e 2e 0a 3e 0a 3e 4d | 61 74 74 68 65 77 20 52 |an..>.>M|atthew R|
|00000790| 69 76 61 73 0a 3e 6d 6c | 72 69 76 61 73 40 69 61 |ivas.>ml|rivas@ia|
|000007a0| 73 74 61 74 65 2e 65 64 | 75 0a 0a 0a 48 69 20 4d |state.ed|u...Hi M|
|000007b0| 61 74 74 68 65 77 2c 0a | 09 49 27 76 65 20 6a 75 |atthew,.|.I've ju|
|000007c0| 73 74 20 62 65 65 6e 20 | 77 6f 72 6b 69 6e 67 20 |st been |working |
|000007d0| 6f 75 74 20 61 20 6d 61 | 74 72 69 78 20 63 6c 61 |out a ma|trix cla|
|000007e0| 73 73 20 6d 79 73 65 6c | 66 2c 20 74 68 65 20 77 |ss mysel|f, the w|
|000007f0| 61 79 20 49 27 76 65 20 | 77 6f 72 6b 65 64 20 69 |ay I've |worked i|
|00000800| 74 20 69 73 0a 74 68 69 | 73 2e 2e 2e 20 4d 79 20 |t is.thi|s... My |
|00000810| 6d 61 74 72 69 78 20 63 | 6c 61 73 73 20 63 6f 6e |matrix c|lass con|
|00000820| 74 61 69 6e 73 20 61 20 | 6d 65 6d 62 65 72 20 3a |tains a |member :|
|00000830| 20 64 6f 75 62 6c 65 20 | 2a 2a 65 6c 65 6d 65 6e | double |**elemen|
|00000840| 74 3b 0a 74 68 69 73 20 | 69 73 20 61 20 70 6f 69 |t;.this |is a poi|
|00000850| 6e 74 65 72 20 74 6f 20 | 61 20 70 6f 69 6e 74 65 |nter to |a pointe|
|00000860| 72 20 74 6f 20 61 20 64 | 6f 75 62 6c 65 20 77 68 |r to a d|ouble wh|
|00000870| 69 63 68 20 68 6f 6c 64 | 73 20 74 68 65 20 6d 61 |ich hold|s the ma|
|00000880| 74 72 69 78 20 65 6c 65 | 6d 65 6e 74 73 3b 0a 49 |trix ele|ments;.I|
|00000890| 6e 20 74 68 65 20 63 6f | 6e 73 74 72 75 63 74 6f |n the co|nstructo|
|000008a0| 72 20 69 20 74 61 6b 65 | 20 74 68 65 20 6e 75 6d |r i take| the num|
|000008b0| 62 65 72 20 6f 66 20 72 | 6f 77 73 20 61 6e 64 20 |ber of r|ows and |
|000008c0| 63 72 65 61 74 65 20 61 | 6e 20 61 72 72 61 79 20 |create a|n array |
|000008d0| 6f 66 20 70 6f 69 6e 74 | 65 72 73 20 74 6f 0a 64 |of point|ers to.d|
|000008e0| 6f 75 62 6c 65 73 20 6c | 69 6b 65 20 74 68 69 73 |oubles l|ike this|
|000008f0| 2c 20 61 6e 64 20 74 68 | 65 6e 20 66 6f 72 20 65 |, and th|en for e|
|00000900| 61 63 68 20 6d 65 6d 62 | 65 72 20 6f 66 20 74 68 |ach memb|er of th|
|00000910| 65 20 61 72 72 61 79 20 | 49 20 63 72 65 61 74 65 |e array |I create|
|00000920| 20 61 6e 20 61 72 72 61 | 79 20 6f 66 0a 64 6f 75 | an arra|y of.dou|
|00000930| 62 6c 65 73 20 77 69 74 | 68 20 61 73 20 6d 61 6e |bles wit|h as man|
|00000940| 79 20 65 6c 65 6d 65 6e | 74 73 20 61 73 20 74 68 |y elemen|ts as th|
|00000950| 65 20 6e 75 6d 62 65 72 | 20 6f 66 20 63 6f 6c 75 |e number| of colu|
|00000960| 6d 6e 73 20 74 68 69 73 | 20 77 6f 72 6b 73 20 6c |mns this| works l|
|00000970| 69 6b 65 20 74 68 69 73 | 3a 0a 0a 74 79 70 65 64 |ike this|:..typed|
|00000980| 65 66 20 64 6f 75 62 6c | 65 2a 20 6d 74 72 78 5f |ef doubl|e* mtrx_|
|00000990| 72 6f 77 3b 20 09 2f 2f | 20 43 72 65 61 74 65 20 |row; .//| Create |
|000009a0| 61 20 74 79 70 65 20 6d | 74 72 78 5f 72 6f 77 20 |a type m|trx_row |
|000009b0| 61 73 20 61 6e 20 0a 09 | 09 09 09 2f 2f 61 6c 69 |as an ..|...//ali|
|000009c0| 61 73 20 66 6f 72 20 70 | 6f 69 6e 74 65 72 20 74 |as for p|ointer t|
|000009d0| 6f 20 64 6f 75 62 6c 65 | 0a 0a 6d 61 74 72 69 78 |o double|..matrix|
|000009e0| 3a 3a 6d 61 74 72 69 78 | 28 69 6e 74 20 72 2c 20 |::matrix|(int r, |
|000009f0| 69 6e 74 20 63 29 0a 7b | 0a 09 72 6f 77 73 20 3d |int c).{|..rows =|
|00000a00| 20 72 3b 09 09 2f 2a 20 | 72 6f 77 73 20 61 6e 64 | r;../* |rows and|
|00000a10| 20 63 6f 6c 73 20 61 72 | 65 20 69 6e 74 20 6d 65 | cols ar|e int me|
|00000a20| 6d 62 65 72 73 20 6f 66 | 20 6d 61 74 72 69 78 20 |mbers of| matrix |
|00000a30| 2a 2f 0a 09 63 6f 6c 73 | 20 3d 20 63 3b 0a 0a 09 |*/..cols| = c;...|
|00000a40| 2f 2a 20 50 6f 69 6e 74 | 20 65 6c 65 6d 65 6e 74 |/* Point| element|
|00000a50| 20 74 6f 20 61 72 72 61 | 79 20 6f 66 20 70 6f 69 | to arra|y of poi|
|00000a60| 6e 74 65 72 73 20 74 6f | 20 64 6f 75 62 6c 65 20 |nters to| double |
|00000a70| 2a 2f 0a 09 65 6c 65 6d | 65 6e 74 20 3d 20 28 64 |*/..elem|ent = (d|
|00000a80| 6f 75 62 6c 65 2a 29 28 | 6e 65 77 20 6d 74 72 78 |ouble*)(|new mtrx|
|00000a90| 5f 72 6f 77 5b 72 6f 77 | 73 5d 29 3b 20 0a 0a 09 |_row[row|s]); ...|
|00000aa0| 2f 2a 20 50 6f 69 6e 74 | 20 65 61 63 68 20 6d 65 |/* Point| each me|
|00000ab0| 6d 62 65 72 20 6f 66 20 | 65 6c 65 6d 65 6e 74 5b |mber of |element[|
|00000ac0| 5d 20 74 6f 20 61 6e 20 | 61 72 72 61 79 20 6f 66 |] to an |array of|
|00000ad0| 20 64 6f 75 62 6c 65 73 | 20 2a 2f 0a 09 66 6f 72 | doubles| */..for|
|00000ae0| 28 75 6e 73 69 67 6e 65 | 64 20 69 6e 74 20 6e 3d |(unsigne|d int n=|
|00000af0| 30 3b 6e 3c 72 6f 77 73 | 3b 6e 2b 2b 29 65 6c 65 |0;n<rows|;n++)ele|
|00000b00| 6d 65 6e 74 5b 6e 5d 20 | 3d 20 6e 65 77 20 64 6f |ment[n] |= new do|
|00000b10| 75 62 6c 65 5b 63 6f 6c | 73 5d 3b 0a 7d 0a 0a 4e |uble[col|s];.}..N|
|00000b20| 6f 77 20 49 27 6d 20 6e | 6f 74 20 73 75 72 65 20 |ow I'm n|ot sure |
|00000b30| 77 68 79 20 79 6f 75 72 | 20 5b 5d 20 6f 70 65 72 |why your| [] oper|
|00000b40| 61 74 6f 72 20 77 6f 72 | 6b 73 2c 20 49 20 74 68 |ator wor|ks, I th|
|00000b50| 6f 75 67 68 74 20 79 6f | 75 20 68 61 64 20 74 6f |ought yo|u had to|
|00000b60| 20 6d 61 6b 65 20 69 74 | 20 61 20 0a 6d 65 6d 62 | make it| a .memb|
|00000b70| 65 72 20 66 75 6e 63 74 | 69 6f 6e 20 6f 66 20 74 |er funct|ion of t|
|00000b80| 68 65 20 63 6c 61 73 73 | 20 69 74 20 77 6f 72 6b |he class| it work|
|00000b90| 65 64 20 6f 6e 20 6d 69 | 6e 65 20 77 6f 72 6b 73 |ed on mi|ne works|
|00000ba0| 20 69 6e 20 6d 75 63 68 | 20 74 68 65 20 73 61 6d | in much| the sam|
|00000bb0| 20 77 61 79 20 74 68 6f | 75 67 68 0a 0a 64 6f 75 | way tho|ugh..dou|
|00000bc0| 62 6c 65 2a 20 6d 61 74 | 72 69 78 3a 3a 6f 70 65 |ble* mat|rix::ope|
|00000bd0| 72 61 74 6f 72 20 5b 5d | 20 28 69 6e 74 20 69 29 |rator []| (int i)|
|00000be0| 20 0a 7b 0a 09 72 65 74 | 75 72 6e 20 65 6c 65 6d | .{..ret|urn elem|
|00000bf0| 65 6e 74 5b 69 5d 3b 0a | 7d 0a 0a 53 6f 20 74 68 |ent[i];.|}..So th|
|00000c00| 69 73 20 72 65 74 75 72 | 6e 73 20 61 20 3c 3c 70 |is retur|ns a <<p|
|00000c10| 6f 69 6e 74 65 72 3e 3e | 20 74 6f 20 74 68 65 20 |ointer>>| to the |
|00000c20| 61 70 70 72 6f 70 72 65 | 61 74 65 20 72 6f 77 2e |appropre|ate row.|
|00000c30| 20 53 6f 20 77 68 65 6e | 20 79 6f 75 20 75 73 65 | So when| you use|
|00000c40| 20 69 74 20 79 6f 75 0a | 67 65 74 0a 74 68 69 73 | it you.|get.this|
|00000c50| 3a 0a 0a 6d 61 74 72 69 | 78 20 41 28 32 2c 32 29 |:..matri|x A(2,2)|
|00000c60| 3b 0a 0a 41 5b 30 5d 5b | 30 5d 20 3d 20 31 3b 0a |;..A[0][|0] = 1;.|
|00000c70| 41 5b 30 5d 5b 31 5d 20 | 3d 20 30 3b 0a 41 5b 31 |A[0][1] |= 0;.A[1|
|00000c80| 5d 5b 30 5d 20 3d 20 30 | 3b 0a 41 5b 31 5d 5b 31 |][0] = 0|;.A[1][1|
|00000c90| 5d 20 3d 20 31 3b 0a 0a | 54 68 69 73 20 77 6f 72 |] = 1;..|This wor|
|00000ca0| 6b 73 20 62 65 63 61 75 | 73 65 3a 20 41 5b 69 5d |ks becau|se: A[i]|
|00000cb0| 20 72 65 74 75 72 6e 73 | 20 74 79 70 65 20 70 6f | returns| type po|
|00000cc0| 69 6e 74 65 72 20 74 6f | 20 64 6f 75 62 6c 65 20 |inter to| double |
|00000cd0| 73 6f 20 77 68 65 6e 20 | 79 6f 75 20 73 74 69 63 |so when |you stic|
|00000ce0| 6b 0a 61 6e 6f 74 68 65 | 72 20 5b 5d 20 6f 6e 20 |k.anothe|r [] on |
|00000cf0| 74 68 65 20 65 6e 64 20 | 79 6f 75 20 67 65 74 20 |the end |you get |
|00000d00| 61 20 6e 6f 72 6d 61 6c | 20 64 6f 75 62 6c 65 20 |a normal| double |
|00000d10| 61 72 72 61 79 20 72 65 | 66 65 6e 63 65 3a 0a 0a |array re|fence:..|
|00000d20| 64 6f 75 62 6c 65 20 2a | 6e 3b 0a 0a 3a 0a 3a 0a |double *|n;..:.:.|
|00000d30| 6e 5b 35 5d 20 3d 20 33 | 3b 0a 0a 49 20 74 68 69 |n[5] = 3|;..I thi|
|00000d40| 6e 6b 20 74 68 69 73 20 | 69 73 20 74 68 65 20 6f |nk this |is the o|
|00000d50| 6e 6c 79 20 77 61 79 20 | 74 6f 20 65 61 73 69 6c |nly way |to easil|
|00000d60| 79 20 72 65 66 65 72 65 | 6e 65 20 6d 65 6d 62 65 |y refere|ne membe|
|00000d70| 72 73 20 6f 66 20 61 20 | 6d 61 74 72 69 78 20 28 |rs of a |matrix (|
|00000d80| 49 20 6b 6e 6f 77 0a 66 | 6f 72 20 73 75 72 65 20 |I know.f|or sure |
|00000d90| 79 6f 75 20 63 61 6e 27 | 74 20 6f 76 65 72 6c 6f |you can'|t overlo|
|00000da0| 61 64 20 74 68 65 20 28 | 29 20 6f 70 65 72 61 74 |ad the (|) operat|
|00000db0| 6f 72 29 20 61 6e 64 20 | 69 74 27 73 20 6d 61 64 |or) and |it's mad|
|00000dc0| 65 20 6f 76 65 72 6c 6f | 61 64 69 6e 67 20 61 6c |e overlo|ading al|
|00000dd0| 6c 0a 74 68 65 20 6f 74 | 68 65 72 20 61 72 69 74 |l.the ot|her arit|
|00000de0| 68 6d 65 74 69 63 20 6f | 70 65 72 61 74 6f 72 73 |hmetic o|perators|
|00000df0| 20 76 65 72 79 20 65 61 | 73 79 2e 20 0a 0a 41 73 | very ea|sy. ..As|
|00000e00| 20 74 6f 20 74 68 65 20 | 73 79 6d 65 74 72 69 63 | to the |symetric|
|00000e10| 20 6d 61 74 72 69 78 20 | 71 75 65 73 74 69 6f 6e | matrix |question|
|00000e20| 3a 0a 0a 43 65 72 74 61 | 69 6e 6c 79 20 79 6f 75 |:..Certa|inly you|
|00000e30| 20 63 6f 75 6c 64 20 6d | 6f 64 69 66 79 20 74 68 | could m|odify th|
|00000e40| 65 20 63 6f 6e 73 74 72 | 75 63 74 6f 72 20 74 6f |e constr|uctor to|
|00000e50| 20 6d 61 6b 65 20 65 61 | 63 68 20 73 75 63 63 65 | make ea|ch succe|
|00000e60| 73 73 69 76 65 20 72 6f | 77 20 61 0a 64 69 66 66 |ssive ro|w a.diff|
|00000e70| 65 72 65 6e 74 20 6c 65 | 6e 67 74 68 2e 20 42 75 |erent le|ngth. Bu|
|00000e80| 74 20 75 73 69 6e 67 20 | 74 68 65 20 5b 5d 20 6f |t using |the [] o|
|00000e90| 70 65 72 61 74 6f 72 20 | 74 6f 20 61 63 63 65 73 |perator |to acces|
|00000ea0| 73 20 69 74 20 69 6e 20 | 74 68 65 20 77 61 79 20 |s it in |the way |
|00000eb0| 79 6f 75 0a 77 61 6e 74 | 20 77 6f 75 6c 64 20 62 |you.want| would b|
|00000ec0| 65 20 74 72 69 63 6b 79 | 2e 20 41 6c 6c 20 49 20 |e tricky|. All I |
|00000ed0| 63 61 6e 20 74 68 69 6e | 6b 20 6f 66 20 77 6f 75 |can thin|k of wou|
|00000ee0| 6c 64 20 62 65 20 69 66 | 20 79 6f 75 20 6d 61 64 |ld be if| you mad|
|00000ef0| 65 20 6d 74 72 78 5f 72 | 6f 77 0a 77 68 69 63 68 |e mtrx_r|ow.which|
|00000f00| 20 49 20 75 73 65 64 20 | 61 62 6f 76 65 20 61 20 | I used |above a |
|00000f10| 63 6c 61 73 73 20 61 73 | 77 65 6c 6c 20 28 77 68 |class as|well (wh|
|00000f20| 69 63 68 20 63 6f 6e 74 | 61 69 6e 65 64 20 61 20 |ich cont|ained a |
|00000f30| 70 6f 69 6e 74 65 72 20 | 74 6f 20 69 74 27 73 20 |pointer |to it's |
|00000f40| 70 61 72 65 6e 74 0a 6d | 61 74 72 69 78 29 20 61 |parent.m|atrix) a|
|00000f50| 6e 64 20 74 68 65 6e 20 | 6d 61 64 65 20 6d 61 74 |nd then |made mat|
|00000f60| 72 69 78 3a 3a 6f 70 65 | 72 61 74 6f 72 5b 5d 20 |rix::ope|rator[] |
|00000f70| 72 65 74 75 72 6e 20 61 | 20 70 6f 69 6e 74 65 72 |return a| pointer|
|00000f80| 20 74 6f 20 61 20 6d 74 | 72 78 5f 72 6f 77 20 61 | to a mt|rx_row a|
|00000f90| 6e 64 0a 6f 76 65 72 6c | 6f 61 64 65 64 20 6d 74 |nd.overl|oaded mt|
|00000fa0| 72 78 5f 72 6f 77 3a 3a | 6f 70 65 72 61 74 6f 72 |rx_row::|operator|
|00000fb0| 5b 5d 20 74 6f 20 6c 6f | 6f 6b 20 61 74 20 69 74 |[] to lo|ok at it|
|00000fc0| 27 73 20 70 61 72 65 6e | 74 73 20 72 6f 77 73 20 |'s paren|ts rows |
|00000fd0| 61 6e 64 20 73 65 65 20 | 77 68 69 63 68 0a 65 6c |and see |which.el|
|00000fe0| 65 6d 65 6e 74 20 74 6f | 20 72 65 74 75 72 6e 2e |ement to| return.|
|00000ff0| 0a 0a 49 20 68 6f 70 65 | 20 74 68 69 73 20 68 65 |..I hope| this he|
|00001000| 6c 70 65 64 20 61 20 62 | 69 74 2e 2e 0a 0a 4a 61 |lped a b|it....Ja|
|00001010| 6d 65 73 20 3a 29 0a 0a | 50 2e 53 2e 20 4d 79 20 |mes :)..|P.S. My |
|00001020| 63 6f 64 65 20 69 73 20 | 6e 6f 74 20 74 6f 74 61 |code is |not tota|
|00001030| 6c 79 20 63 6f 6d 70 6c | 65 74 65 20 79 65 74 20 |ly compl|ete yet |
|00001040| 62 75 74 20 69 66 20 79 | 6f 75 27 64 20 6c 69 6b |but if y|ou'd lik|
|00001050| 65 20 49 27 6c 6c 20 73 | 65 6e 64 20 79 6f 75 20 |e I'll s|end you |
|00001060| 77 68 61 74 0a 49 27 76 | 65 20 67 6f 74 20 73 6f |what.I'v|e got so|
|00001070| 20 66 61 72 2e 2e 2e 0a | 0a                      | far....|.       |
+--------+-------------------------+-------------------------+--------+--------+