MATLAB: How to run a 3×3 matrix through a for loop and save all instances of the [3×3]

3d matrixfor loopmatrix manipulation

I have a [3×3] transformation matrix A = [ -sind(omega*t), cosd(omega*t), 0; cosd(omega*t), sind(omega*t) cosd(phi); cosd(omega*t), sind(omega*t), sin(phi)]

omega and phi are constants defined earlier. t is the vaiable that is being looped for. if I have 300 values for t, I would like to output 300 different [3×3] matricies, each one corresponding with a different value of t. for more information t is a value that is being read in from a data sheet.

Best Answer

A is a cell array the same size as t where A{n} is the matrix for t(n).

omega = 1; 
phi = 1; 
t = linspace(0,5,300);
A = arrayfun(@(t)[-sind(omega*t), cosd(omega*t), 0; 
    cosd(omega*t), sind(omega*t) cosd(phi); 
    cosd(omega*t), sind(omega*t), sin(phi)],t,'UniformOutput',false);

Related Solutions

MATLAB: Using sin as part of a longer equation

Use .* instead of *

MATLAB: Multiplying 3X3 array by a 3×1

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);

Best Answer

Related Solutions

MATLAB: Using sin as part of a longer equation

MATLAB: Multiplying 3X3 array by a 3×1

Related Question