Cross Product

This is a discussion on Cross Product within the A Brief History of Cprogramming.com forums, part of the Community Boards category; Does anyone know how to derive the cross product formula from the dot product formula? My algebra teacher did it ...

  1. #1
    C++ Developer XSquared's Avatar
    Join Date
    Jun 2002
    Location
    Ontario, Canada
    Posts
    2,718

    Cross Product

    Does anyone know how to derive the cross product formula from the dot product formula? My algebra teacher did it last semester, but I can't find the note, and I can't figure it out myself.
    Naturally I didn't feel inspired enough to read all the links for you, since I already slaved away for long hours under a blistering sun pressing the search button after typing four whole words! - Quzah

    You. Fetch me my copy of the Wall Street Journal. You two, fight to the death - Stewie

  2. #2
    Intranasal Heroin User Xterria's Avatar
    Join Date
    Sep 2001
    Location
    Buffalo, NY
    Posts
    1,035

  3. #3
    C++ Developer XSquared's Avatar
    Join Date
    Jun 2002
    Location
    Ontario, Canada
    Posts
    2,718
    Uhh... I'm not exactly sure what relevance that program has to my question. Let me rephrase it and see if I can clarify.

    I want to know how to go from the dot product formula to the cross product formula. There is a way (I think).
    Naturally I didn't feel inspired enough to read all the links for you, since I already slaved away for long hours under a blistering sun pressing the search button after typing four whole words! - Quzah

    You. Fetch me my copy of the Wall Street Journal. You two, fight to the death - Stewie

  4. #4
    Intranasal Heroin User Xterria's Avatar
    Join Date
    Sep 2001
    Location
    Buffalo, NY
    Posts
    1,035
    oh, lol, sorry. ok i'm pretty sure this is want you're looking for:
    http://www.lfcs.inf.ed.ac.uk/reports...S-LFCS-96-345/
    hope that helps.

  5. #5
    C++ Developer XSquared's Avatar
    Join Date
    Jun 2002
    Location
    Ontario, Canada
    Posts
    2,718
    Eep! That's a 179-page doctorate thesis! What I want has nothing to do with calculus. It's linear algebra (vectors in 3-space).
    Naturally I didn't feel inspired enough to read all the links for you, since I already slaved away for long hours under a blistering sun pressing the search button after typing four whole words! - Quzah

    You. Fetch me my copy of the Wall Street Journal. You two, fight to the death - Stewie

  6. #6
    Intranasal Heroin User Xterria's Avatar
    Join Date
    Sep 2001
    Location
    Buffalo, NY
    Posts
    1,035
    details, details. I guess i'm just not good enough for you.

  7. #7
    ¡Amo fútbol!
    Join Date
    Dec 2001
    Posts
    2,136
    Or maybe you're purposely being an ass.

  8. #8
    & the hat of GPL slaying Thantos's Avatar
    Join Date
    Sep 2001
    Posts
    5,681
    Does the truth hurt Xterria?

  9. #9
    Registered User
    Join Date
    Mar 2004
    Posts
    494
    i took linear algebra last semester the forumla goes as follows

    if u=(u1, u2, u3) and v=(v1,v2,v3) the cross product is u xv.

    u xv = (u2v3 -u3v2, u3v1 - u1v3, u1v2 -u2v1) u can do turn this into matrix form if u want.

    dot product aka Euclidean inner product is the same as above only with Un and Vn .
    u=(u1, y2, u3..Un) and v=(v1,v2,v3,Vn) and the product is defined by
    u xv = (u1v1 + u2v2, + .. UnVn)
    Last edited by InvariantLoop; 04-23-2004 at 04:35 PM. Reason: small typo
    When no one helps you out. Call google();

  10. #10
    C++ Developer XSquared's Avatar
    Join Date
    Jun 2002
    Location
    Ontario, Canada
    Posts
    2,718
    I know the formulas for dot and cross products. I'm just trying to figure out how to get the cross product formula using only the dot product formula.
    Naturally I didn't feel inspired enough to read all the links for you, since I already slaved away for long hours under a blistering sun pressing the search button after typing four whole words! - Quzah

    You. Fetch me my copy of the Wall Street Journal. You two, fight to the death - Stewie

  11. #11
    Registered User
    Join Date
    Mar 2004
    Posts
    494
    i think its very obvious cant u see it? they only differ in 2 things, 1 has Un and Vn which doesnt matter at all, and the other thing is that one has subtraction and the other has addition so all u gotta do is make the prog so it takes the subtraction and change it to addition and u got ur dot product.
    When no one helps you out. Call google();

  12. #12
    C++ Developer XSquared's Avatar
    Join Date
    Jun 2002
    Location
    Ontario, Canada
    Posts
    2,718
    What I'm looking to do is to find out exactly how the equation for cross product is created.
    Naturally I didn't feel inspired enough to read all the links for you, since I already slaved away for long hours under a blistering sun pressing the search button after typing four whole words! - Quzah

    You. Fetch me my copy of the Wall Street Journal. You two, fight to the death - Stewie

  13. #13
    Registered User
    Join Date
    Mar 2004
    Posts
    494
    u already have the equation, what u need is a way to make it so the machine can understand it.

    i can think of an example but no idea if this is correct.

    create 2 arrays, u and v, those arrays got elements in them, u1, v1 etc.. since u already know the equation now u gotta multiply the elemts in 1 array with the elemnts of the other array in this way as the equation states (u2v3 -u3v2, u3v1 - u1v3, u1v2 -u2v1) .
    When no one helps you out. Call google();

  14. #14
    C++ Developer XSquared's Avatar
    Join Date
    Jun 2002
    Location
    Ontario, Canada
    Posts
    2,718
    This has nothing to do with programming. I know the formulae, and I know how to implement them. I am just trying to figure out how you get the cross product formula from the dot product formula. Simple pen and paper.
    Naturally I didn't feel inspired enough to read all the links for you, since I already slaved away for long hours under a blistering sun pressing the search button after typing four whole words! - Quzah

    You. Fetch me my copy of the Wall Street Journal. You two, fight to the death - Stewie

  15. #15
    Registered User
    Join Date
    Mar 2004
    Posts
    494
    u need the proof for each 1 then
    When no one helps you out. Call google();

Page 1 of 2 12 LastLast
Popular pages Recent additions subscribe to a feed

Similar Threads

  1. How Can I draw What I want?
    By CChakra in forum Game Programming
    Replies: 22
    Last Post: 09-11-2008, 09:38 AM
  2. cross product?
    By kypronite in forum Game Programming
    Replies: 8
    Last Post: 09-07-2008, 12:15 PM
  3. Minimax, URGENT :(
    By Dark-MX0Z in forum C++ Programming
    Replies: 6
    Last Post: 11-14-2007, 06:29 AM
  4. IE 6 status bar
    By DavidP in forum Tech Board
    Replies: 15
    Last Post: 10-23-2002, 06:31 PM

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21