MATLAB Answers

Function Return only one value

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Tipu Sultan
Tipu Sultan on 15 May 2019
Commented: Tipu Sultan on 16 May 2019
My Code is as follows:
function [X,Y] = MyEKFFun(theta1,theta2,theta3,r1,r2,r3,t1,t2,t3,T)
S = [100 0 0 0 0 0;
0 100 0 0 0 0;
0 0 100 0 0 0;
0 0 0 100 0 0;
0 0 0 0 100 0;
0 0 0 0 0 100];
prev_S = S;
Big_lambda = eye(3);
a=0;
b=0;
c=0;
p=0;
q=0;
s=0;
est_vec=[ a ; b; c; p; q; s];
%theta = [ 31 24 18] ;
%t= [ 1 1.1 1.2 ];
%r= [330 364 379];
theta = [ theta1 theta2 theta3] ;
t= [ t1 t2 t3 ];
r= [r1 r2 r3];
%Wanted = num2cell(M,1)
%[r,b,distance,angle]=deal(Wanted{:})
x = [ r; theta ; t];
%dif_x=zeros(2,3);
dif_a = arrayfun(@(t) [t^2 t 1 0 0 0; 0 0 0 t^2 t 1],t,'UniformOutput',false);
%time=2;
time=T;
dif_x = zeros(2, 3, 3); % Pre-allocation
w = zeros(2, 1, 3); % Pre-allocation
%pred_x = zeros(3, 3, 3);
W = zeros(2,2);
y = zeros(2, 1, 3);
K = zeros(6, 2, 3);
for i=1:3
dif_x(:, :, i) = [-cos(theta(i)), r(i).*sin(theta(i)), 2*a.*t(i)+b;...
-sin(theta(i)), -r(i).*cos(theta(i)), 2*p.*t(i)+q];
W(:,:,i) = dif_x(:,:,i)*Big_lambda(i)*dif_x(:,:,i)';
pred_x = x(:,i)+randn(3,1);
w(:,:,i) = dif_x(:,:,i) * (x(:,i)-pred_x);
y(:,:,i) = dif_a{i} * est_vec + w(:,:,i);
K(:,:,i) = prev_S*dif_a{i}'/((W(:,:,i) + dif_a{i}*prev_S*dif_a{i}'));
est_vec_new = est_vec + K(:,:,i)*(y(:,:,i)-dif_a{i}*est_vec);
cond = abs(est_vec_new - est_vec);
if cond < 0.003
break
end
est_vec = est_vec_new;
a=est_vec(1,1);
b=est_vec(2,1);
c=est_vec(3,1);
p=est_vec(4,1);
q=est_vec(5,1);
s=est_vec(6,1);
S_new = (eye(6) - (K(:,:,i)*dif_a{i}))*prev_S;
prev_S = S_new;
%X(i) = a*time.^2+b*time+c; % To calculate x co-ordinate for t>=3
%Y(i) = p*time.^2+q*time+s; % To calculate y co-ordinate for t>=3
%figure,plot(t,meas_equa1)
%new_t=[t,time];
%figure,plot(r_cosTheta,r_sineTheta)
end
X = a*time.^2+b*time+c; % To calculate x co-ordinate for t>=3
Y = p*time.^2+q*time+s;
end
Now my question is why it returns only one values as 'ans'.It should be two values which is calculated as 'X,Y' from the updated values of the for loop.But the function always returns one value titled answer, like as follows:
>> MyEKFFun(31,24,18,330,364,379,1,1.1,1.3,2)
ans =
384.4037
Please help anyone.
Thanks in advance.

Answers (2)

James Tursa
James Tursa on 15 May 2019
Edited: James Tursa on 15 May 2019
Call it with two requested outputs:
[X,Y] = MyEKFFun(31,24,18,330,364,379,1,1.1,1.3,2)
Since you were calling it with no requested outputs, MATLAB simply put the first one in ans and threw away the second one.
  1 Comment
Tipu Sultan
Tipu Sultan on 16 May 2019
Ok thanks.
Can you tell me my code is correct or my implementation is correct or not!
My algorithm is as follows:

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Jon Wieser
Jon Wieser on 15 May 2019
when you call the function, you need to specify two outputs,
for example:
[X,Y] =MyEKFFun(31,24,18,330,364,379,1,1.1,1.3,2)

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