# Multiplying 3X3 array by a 3x1

15 vues (au cours des 30 derniers jours)
Tommy Pestolesi le 1 Jan 2020
Hello I am here trying to multiply contents of a 3x3 array by a 3x1 vector. The code I have developed is displayed below. The outputs I have for matricies C through H are what I am looking for but when I try to do some matrix math I get different Arrays with not quite the right outputs.
clear all;
close all;
% Import the data file
M = importdata('6x300_input_data.txt');
%u,v,w are inputs taken from the data file that are each their own column
u = M.data(:,3);
v = M.data(:,4);
w = M.data(:,5);
% Time variable in seconds that is pulled from data
t_in = M.data(:,6);
lamda = -60; %longitude in degrees
omega = 0.004; %Rate
phi = 30; %measurement in degrees
UVW = [u,v,w];
%Array to populate the serires of A matrices that will be multiplied by
%each instance of UVW
A = arrayfun(@(t_in)[ -sind(lamda - omega*t_in) cosd(lamda - omega*t_in) 0;
-sind(phi)*cosd(lamda-omega*t_in) -sind(phi)*sind(lamda - omega*t_in) cosd(phi);
cosd(phi)*cosd(lamda - omega*t_in) cosd(phi)*sind(lamda - omega*t_in) sind(phi)],t_in,'UniformOutput',false);
%proper outputs that are desired but want to find a better way...
C = A{1,1}*UVW(1,:)'
D = A{2,1}*UVW(2,:)'
E = A{3,1}*UVW(3,:)'
F = A{4,1}*UVW(4,:)'
G = A{5,1}*UVW(5,:)'
H = A{6,1}*UVW(6,:)'
disp(C:H);
##### 0 commentairesAfficher -2 commentaires plus anciensMasquer -2 commentaires plus anciens

Connectez-vous pour commenter.

### Réponse acceptée

Max Murphy le 2 Jan 2020
You can probably improve on this and in terms of actual efficiency I am not sure it's better than what you have, but I am assuming you wanted something that makes it so you don't run a loop on all the matrix multiplies:
%%%% OLD %%%%
clear all;
close all;
%% Import the data file
M = importdata('6x300_input_data.txt');
%% u,v,w are inputs taken from the data file that are each their own column
u = M.data(:,3);
v = M.data(:,4);
w = M.data(:,5);
%% Time variable in seconds that is pulled from data
t_in = M.data(:,6);
lambda = -60; %longitude in degrees
omega = 0.004; %Rate
phi = 30; %measurement in degrees
UVW = [u,v,w];
%% Array to populate the series of A matrices that will be multiplied by
%each instance of UVW
A = arrayfun(@(t_in)[ -sind(lambda - omega*t_in) cosd(lambda - omega*t_in) 0;
-sind(phi)*cosd(lambda-omega*t_in) -sind(phi)*sind(lambda - omega*t_in) cosd(phi);
cosd(phi)*cosd(lambda - omega*t_in) cosd(phi)*sind(lambda - omega*t_in) sind(phi)],t_in,'UniformOutput',false);
%% proper outputs that are desired but want to find a better way...
C = A{1,1}*UVW(1,:)'
D = A{2,1}*UVW(2,:)'
E = A{3,1}*UVW(3,:)'
F = A{4,1}*UVW(4,:)'
G = A{5,1}*UVW(5,:)'
H = A{6,1}*UVW(6,:)'
disp(C:H);
%%%% NEW %%%%
%% General Idea:
a = A{2,1}(:);
b = repmat(UVW(2,:),3,1);
b = b(:);
p = a.*b; % individual products
%% Implement:
A_hat = [ -sind(lambda - omega*t_in), ...
cosd(lambda - omega*t_in), ...
zeros(size(t_in)), ...
-sind(phi)*cosd(lambda-omega*t_in), ...
-sind(phi)*sind(lambda - omega*t_in), ...
ones(size(t_in))*cosd(phi), ...
cosd(phi)*cosd(lambda - omega*t_in), ...
cosd(phi)*sind(lambda - omega*t_in), ...
ones(size(t_in))*sind(phi)];
B_hat = repmat(UVW,1,3);
P = A_hat .* B_hat;
%% I think differences may just be finite-math issues:
output = [sum(P(:,1:3),2), sum(P(:,4:6),2), sum(P(:,7:9),2)].';
disp('output(:,1) - C:');
disp(output(:,1) - C);
disp('output(:,2) - D:');
disp(output(:,2) - D);
disp('output(:,3) - E:');
disp(output(:,3) - E);
disp('output(:,4) - F:');
disp(output(:,4) - F);
disp('output(:,5) - G:');
disp(output(:,5) - G);
disp('output(:,6) - H:');
disp(output(:,6) - H);
##### 1 commentaireAfficher -1 commentaires plus anciensMasquer -1 commentaires plus anciens
Tommy Pestolesi le 7 Jan 2020
Thank you for your help and insight Max!

Connectez-vous pour commenter.

### Catégories

En savoir plus sur Whos dans Help Center et File Exchange

### Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by