Normpdf is behaving strangely
Thus,
function ret = f(pIx5, dS)
sigma = 1;
rho = dS(1);
theta = dS(2);
mu_x = rho*cos(theta);
display(pIx5);
display(mu_x);
pdf = normpdf(pIx5, mu_x, sigma);
ret = max(pdf);
end
The following error message appears:
pIx5 =
54 65 11 0 0
mu_x =
11.9218
Error using normpdf (line 36) Non-scalar arguments must match in size.
Error in f (line 11)
pdf = normpdf(pIx5, mu_x, sigma);
But it works fine in the following order:
function ret = f(pIx5, dS)
sigma = 1;
rho = dS(1);
theta = dS(2);
pIx5 = [54,65, 11, 0, 0];
mu_x = 11.9218;
display(pIx5);
display(mu_x);
pdf = normpdf(pIx5, mu_x, sigma);
ret = max(pdf);
end
What's going on here?
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I'm willing to bet significant amounts of money if the problem is with the type of your input pIx5
. Note:
>> pdf = normpdf([54 65 11 0 0], 11.9218, 1); % Works fine
>> pdf = normpdf(uint8([54 65 11 0 0]), 11.9218, 1);
Error using normpdf (line 36)
Non-scalar arguments must match in size.
Why is it giving a size error for what should be type related? Taking a look at the code normpdf
will answer this. From lines 33-37, R2016b:
...
try
y = exp(-0.5 * ((x - mu)./sigma).^2) ./ (sqrt(2*pi) .* sigma);
catch
error(message('stats:normpdf:InputSizeMismatch'));
end
Basically, any error in evaluating this equation is reported as a size mismatch error. In this case, the real problem with exp
not working for integer data types (it only supports single
and double
types):
>> x = uint8([54 65 11 0 0]);
>> mu = 11.9218;
>> sigma = 1;
>> y = exp(-0.5 * ((x - mu)./sigma).^2) ./ (sqrt(2*pi) .* sigma);
Undefined function 'exp' for input arguments of type 'uint8'.
Solution then? Just leave your offending inputs first, single
or double
:
pdf = normpdf(double(pIx5), mu_x, sigma);
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