Multiplying matrices and vectors in loop

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Tea Arrigoni 2017-12-14

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/372942-multiplying-matrices-and-vectors-in-loop

评论： Tea Arrigoni 2017-12-14

This is the part of the code I want to solve but it gives me error, says that the matrix size are not the same but they are all 3 x 3. Do I need a for loop maybe? Can you help with it?

clear all, clc; H=1700 %height

dSG=0.129*H;

dH=0.185*H;

dF=0.146*H;

FiA = -10:20:170 ;

FiFm = -60:10:170 ;

FiRm=-60:20:90;

FiEF=-90:20:60;

COSA=cosd(FiA);

SINA=sind(FiA);

RA = arrayfun( @(sinFif, cosFif) [cosFif 0 sinFif; 0 1 0; -sinFif 0 cosFif], SINA, COSA, 'uniform', 0)

CA=cell2mat(RA)

COSE=cosd(FiEF);

SINE=sind(FiEF);

RE = arrayfun( @(sinFif, cosFif) [cosFif 0 sinFif; 0 1 0; -sinFif 0 cosFif], SINE, COSE, 'uniform', 0)

CE=cell2mat(RE)

[gFiA, gFiFm] = ndgrid(FiA, FiFm);%you want all combinations

gFiF = gFiFm + gFiA / 3 ;

COSF = cosd(gFiF); %cosd and sind because you are working in degrees !

SINF = sind(gFiF );

RF = arrayfun( @(sinFif, cosFif) [1 0 0; 0 cosFif -sinFif; 0 sinFif cosFif], SINF, COSF, 'uniform', 0)

CF=cell2mat(RF)

rSG=[-dSG 0 0]'; %shoulder joint - torso

rH=[0 0 -dH]' ;% upper arm

rF=[0 dF 0]';%fore arm

rW=rSG+CA*CF*rH+CE*rF

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Answer 1

KL 2017-12-14

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https://ww2.mathworks.cn/matlabcentral/answers/372942-multiplying-matrices-and-vectors-in-loop#answer_296222

在 MATLAB Online 中打开

they are all 3 x 3...

No, they are not. Check the output for the following

 size(CA)
 size(CF)

and the other matrices you have.

Just copy-pasting the code doesn't help either. What exactly do you want to do?

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Tea Arrigoni 2017-12-14

That is correct. Sorry for that. I am relatively new in Matlab. I will send you in the attachment what I need but in short I need to recreate all point that a human wrist can reach in workspace for an exoskeleton-rehabilitation device we are trying to build (My PhD). I have three angles in shoulder FiA, FiF and FiR, and I have one FiEF in elbow and in correlation of shoulder and elbow movement I want to get a cloud of points in a workspace. I have all formulas but I have to make the whole iteration i MatLab. I managed to compute point by point (just tested it) but I need it for the whole area. The formulas you can see attached. Can you help regarding this issue?

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