Why does my loop stop after the first iteration?
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Hi everyone! I am trying to generate a sample (either a 0 or 1) with certain probability, and then update a Mean formula and Variance formula, both of which are recursive. I will keep generating samples and keep updating the formulas until this condition is met:
if (n>10) && ((Mn_A(A,n)-2*sqrt(Vn_A(A,n)/n)>.05) || (Mn_A(A,n)+2*sqrt(Vn_A(A,n)/n) < 0.5))
disp(['95% confidence interval achieved for A with N = ' num2str(n) ' and width = ' num2str(WidthA)])
break
end
I am getting an error however. It goes through the loop on the n=1 iteration with no problem, but on n=2, I get this error:
Not enough input arguments.
Error in ee497ca2_1>Mn_A (line 14)
if n == 0
Error in ee497ca2_1>Mn_A (line 19)
r = (Mn_A(n-1) + (x1 - Mn_A(n-1)))/n;
Error in ee497ca2_1 (line 4)
Mn_A(A,n)
I think I am missing something on how recursion works, but I am not sure. Here is the whole code below. Thank you!
samples = 500;
for n = 1:samples
A = randsrc(1,1,[0,1;0.49,0.51]);
Mn_A(A,n)
Vn_A(A,n)
ConfidenceInterval_Min_A = Mn_A(A,n) - 2*sqrt(Vn_A(A,n)/n);
ConfidenceInterval_Max_A = Mn_A(A,n) + 2*sqrt(Vn_A(A,n)/n);
WidthA = ConfidenceInterval_Max_A - ConfidenceInterval_Min_A;
if (n>10) && ((Mn_A(A,n)-2*sqrt(Vn_A(A,n)/n)>.05) || (Mn_A(A,n)+2*sqrt(Vn_A(A,n)/n) < 0.5))
disp(['95% confidence interval achieved for A with N = ' num2str(n) ' and width = ' num2str(WidthA)])
break
end
end
function r = Mn_A(x1,n)
if n == 0
r = 0;
elseif n == 1
r = x1;
else
r = (Mn_A(n-1) + (x1 - Mn_A(n-1)))/n;
end
end
function q = Vn_A(x1,n)
if n == 0
q = 0;
elseif n == 1
q = 0;
else
q = Vn_A(n-1) - Vn_A(n-1)/(n-1) + ((x1-Mn_A(n-1))^2)/n;
end
end
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Accepted Answer
Voss
on 26 Apr 2022
Edited: Voss
on 26 Apr 2022
Mn_A takes 2 input arguments, x1 and n:
function r = Mn_A(x1,n)
But later in the function Mn_A, you call Mn_A with one input:
r = (Mn_A(n-1) + (x1 - Mn_A(n-1)))/n;
% ^^^ ^^^ one input each time
When Mn_A is called with one input, it has an error on its first line:
function r = Mn_A(x1,n) % if only x1 is given, n is undefined, so
if n == 0 % there's an error trying to refer to n here
(Same for Vn_A.)
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