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elica85
matrix multiplication
comp being slow, pls wait..
ok what is the matrix problem
let x be an arbitrary angle and C represents cosine, S represent Sine
and what are the dimensions of those matrices
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
and Y another arbitrary angle..
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
i guess my problem is more towards trig...is there a simple expressions for each element?
i will solve for u as soon as i am done with the other student
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
4x4 is a messy matrix, so should expect such a mess
ok. or are you familiar with matlab? from what i remember, you have to have values for matlab...
do u want to do this with matlab or using normal mathematical methods
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
ok i will do it for u with c++ or c sharp
so u just want to multiply those two matrices
i'm not familiar with c++ but there is another matrix, i will type it up..
Matrix C= CZ -SZ 0 cCZ SZ CZ 0 cSZ 0 0 1 0 0 0 0 1
and a,b,c are arbitrary constants. so in c++, you can keep the expression with variables?
if that means the same thing as AxB=AB ABxC=result 4x4 matrix
no it does not mean the same thing but i get what u want now
am sorry of the delay just someone before u sent me a bunch of questions that i need to type the answers
so u can do others stuff and i will finish the work for u as soon as possible
that's fine, i will check later
sorry for keeping u waiting but i need to know do u want element by element multiplication or linear algebraic product
you have to be precise on that so i can give u the right answer
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
HI THERE I KNOW IT TOOK ME A LONG TIME BUT I PROMISED SOMEONE TO FINISH THERE 50 QUESTIONS
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;
the result for linear algebraic multiplication for example A x B
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]
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]
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
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]
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.
Sorry i was busy but i have to keep all my promises not matter what, so all the best and good luck.
Now with this basic method you can do whatever multiplication you want, and in any associative, distributive ... way you want.
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!