Quantcast

A community for students. Sign up today!

Here's the question you clicked on:

55 members online
  • 0 replying
  • 0 viewing

elica85

  • one year ago

matrix multiplication

  • This Question is Closed
  1. elica85
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    comp being slow, pls wait..

  2. mathsmind
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    ok what is the matrix problem

  3. elica85
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    let x be an arbitrary angle and C represents cosine, S represent Sine

  4. mathsmind
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    and what are the dimensions of those matrices

  5. elica85
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    matrix A= CX -SX 0 aCX SX CX 0 aSX 0 0 1 0 0 0 0 1 matrix B= CY -SY 0 bCY SY CY 0 bSY 0 0 1 0 0 0 0 1

  6. elica85
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    and Y another arbitrary angle..

  7. elica85
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    4x4 matrix

  8. elica85
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    i think i get how to do the multiplication but since there are variables, i'm coming up with crazy figures for each new element in the new matrix. and this new matrix has to be multiplied by another 4x4

  9. mathsmind
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    ok

  10. elica85
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    i guess my problem is more towards trig...is there a simple expressions for each element?

  11. mathsmind
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    i will solve for u as soon as i am done with the other student

  12. elica85
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    thx, or you can just tell me if there's no simple expression cuz i can do all the work, it will just look messy

  13. mathsmind
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    4x4 is a messy matrix, so should expect such a mess

  14. elica85
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    ok. or are you familiar with matlab? from what i remember, you have to have values for matlab...

  15. mathsmind
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    do u want to do this with matlab or using normal mathematical methods

  16. elica85
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    it's just part of the actual problem so i don't think working it out by hand is important so if i can do it on matlab, it would be great

  17. elica85
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    or calculator

  18. mathsmind
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    ok i will do it for u with c++ or c sharp

  19. mathsmind
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    so u just want to multiply those two matrices

  20. elica85
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    i'm not familiar with c++ but there is another matrix, i will type it up..

  21. elica85
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    Matrix C= CZ -SZ 0 cCZ SZ CZ 0 cSZ 0 0 1 0 0 0 0 1

  22. elica85
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    and a,b,c are arbitrary constants. so in c++, you can keep the expression with variables?

  23. mathsmind
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    do u want AxBxC

  24. elica85
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    if that means the same thing as AxB=AB ABxC=result 4x4 matrix

  25. mathsmind
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    ok

  26. mathsmind
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    no it does not mean the same thing but i get what u want now

  27. elica85
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    ok thx

  28. mathsmind
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    am sorry of the delay just someone before u sent me a bunch of questions that i need to type the answers

  29. mathsmind
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    so u can do others stuff and i will finish the work for u as soon as possible

  30. elica85
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    that's fine, i will check later

  31. mathsmind
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    sorry for keeping u waiting but i need to know do u want element by element multiplication or linear algebraic product

  32. mathsmind
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    you have to be precise on that so i can give u the right answer

  33. elica85
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    good question, i was actually trying to figure out on google. all the instructor said was to multiply them. what i found on google was this http://easycalculation.com/matrix/learn-matrix-multiplication.php which is what's going to make the result matrix look real messy. the problem is to find the transformation matrix of a mechanical grabber. so it would have multiple joints, point O as fixed, and point P as the position of the grabber. to find the position, find transformation matrices (which i've done) and the post multipy the matrices to get the result matrix. the matrix C was from point O to joint 1, matrix B is from joint 1 to joint 2, and matrix A is from joint 2 to point P

  34. mathsmind
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    HI THERE I KNOW IT TOOK ME A LONG TIME BUT I PROMISED SOMEONE TO FINISH THERE 50 QUESTIONS

  35. mathsmind
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    syms cosx sinx asinx acosx cosy siny bcosy bsiny cosz sinz csinz ccosz syms cosx sinx asinx acosx cosy siny bcosy bsiny cosz sinz csinz ccosz A=[cosx, -sinx,0, acosx;sinx,cosx,0,asinx;0,0,1,0;0,0,0,1]; B=[cosy, -siny,0, bcosy;siny,cosy,0,bsiny;0,0,1,0;0,0,0,1]; %C=[cosz, -sinz,0, ccosz;sinz,cosz,0,csinz;0,0,1,0;0,0,0,1]; %Linear algebraic product of the matrices... M1= A * B * C; M2= A*B; M3= B*C; M4= A*C; %Array arithmetic operations are carried out element by element M1= A * B * C; M2= A*B; M3= B*C; M4= A*C;

  36. mathsmind
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    the result for linear algebraic multiplication for example A x B

  37. mathsmind
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    A = [ cosx, -sinx, 0, acosx] [ sinx, cosx, 0, asinx] [ 0, 0, 1, 0] [ 0, 0, 0, 1]

  38. mathsmind
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    B = [ cosy, -siny, 0, bcosy] [ siny, cosy, 0, bsiny] [ 0, 0, 1, 0] [ 0, 0, 0, 1]

  39. mathsmind
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    A*B ans = [ cosx*cosy - sinx*siny, - cosx*siny - cosy*sinx, 0, acosx + bcosy*cosx - bsiny*sinx] [ cosx*siny + cosy*sinx, cosx*cosy - sinx*siny, 0, asinx + bsiny*cosx + bcosy*sinx] [ 0, 0, 1, 0] [ 0, 0, 0, 1]

  40. mathsmind
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    so this is what u called messy result which seems to be exclusive of your intuitive expectation, however the element by element matrix multiplication would give a result hopefully to your expectation

  41. mathsmind
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    A.*B ans = [ cosx*cosy, sinx*siny, 0, acosx*bcosy] [ sinx*siny, cosx*cosy, 0, asinx*bsiny] [ 0, 0, 1, 0] [ 0, 0, 0, 1]

  42. mathsmind
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    Array arithmetic operations are carried out element by element, and can be used with multidimensional arrays. The period character (.) distinguishes the array operations from the matrix operations.

  43. mathsmind
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    Sorry i was busy but i have to keep all my promises not matter what, so all the best and good luck.

  44. mathsmind
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    Now with this basic method you can do whatever multiplication you want, and in any associative, distributive ... way you want.

  45. elica85
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    thank you, i think i will have to ask which multiplication is needed since i don't know. i would hope it's the easier one though!

  46. Not the answer you are looking for?
    Search for more explanations.

    Search OpenStudy
    • Attachments:

Ask your own question

Ask a Question
Find more explanations on OpenStudy

Your question is ready. Sign up for free to start getting answers.

spraguer (Moderator)
5 → View Detailed Profile

is replying to Can someone tell me what button the professor is hitting...

23

  • Teamwork 19 Teammate
  • Problem Solving 19 Hero
  • You have blocked this person.
  • ✔ You're a fan Checking fan status...

Thanks for being so helpful in mathematics. If you are getting quality help, make sure you spread the word about OpenStudy.

This is the testimonial you wrote.
You haven't written a testimonial for Owlfred.