Operands to the logical AND (&&) and OR (||) operators must be convertible to logical scalar values. Use the ANY or ALL functions to reduce operands to logical scalar values.

function [y,Err,n] = ARCTANA(x)
[rows,columns]=size(x);
y_plot=zeros(rows,columns);
err_plot=zeros(rows,columns);
n_plot=zeros(rows,columns);

for f=1:rows
for g=1:columns
v=x(f,g);
if v<=-1
N=50;

y=(-pi/2);
    for k=0:N
    an=((-1)^k)/((2*k+1)*(v^(2*k+1)));
    y=y-an;
    end
real=atan(v);
Err=abs(real-y);
n=N;

elseif -1<v & v<1
an=v;
y=an;
k=1;
    while abs(an)>1E-12
    an=(((-1)^k)*v^(2*k+1)/(2*k+1));
    y=y+an;
    k=k+1;
    end
real=atan(v);
Err=abs(real-y);
n=k-1;
else
an=1/v;
y=(pi/2);
k=0;

    while abs(an)>1E-12 & k<=50
    an=((-1)^k)/((2*k+1)*(v^(2*k+1)));
    y=y-an;
    k=k+1;
    end
real=atan(v);
Err=abs(real-y);
n=k;
end
y_plot(f,g)=y;
y=y_plot;
n_plot(f,g)=n;
n=n_plot
err_plot(f,g)=Err;
Err=err_plot;
end
end

This is the code I wrote

******* GRADING OUTPUT *******
Function name.......CORRECT
       inputs.......CORRECT +1 points
      outputs.......CORRECT +1 points

Calling function [y, Err, n] = ARCTANA(1 x 1 array)
	Grading variable y........correct size +0.5 points
                          ....correct value +0.5 points
	Grading variable Err........correct size +0.5 points
                            ....correct value +0.5 points
	Grading variable n........correct size +0.5 points
                          ....correct value +0.5 points

Calling function [y, Err, n] = ARCTANA(3 x 5 array)
	Grading variable y........correct size +0.5 points
                          ....correct value +0.5 points
	Grading variable Err........correct size +0.5 points
                            ....correct value +0.5 points
	Grading variable n....Operands to the logical AND (&&) and OR (||) operators must be convertible to logical scalar values. Use the ANY or ALL functions to reduce operands to logical
scalar values.

Error in TestARCTANA

Error in TestARCTANA

Error in TestARCTANA
 

This is the output of the P-code and I am confused on what is wrong. If I enter a "test" array myself through the function it works just fine.

[Walter Roberson]

n_plot(f,g)=n;
n=n_plot

That is suspicious, that you are returning a 2 d array for n.

[Catalytic]

I highly recommend against "f" and "g" as symbols for loop indices. It is terribly unreadable to others -

for f=1:rows
for g=1:columns

Answer 1

[Walter Roberson]

You would get this error if the grading system is expecting n to be a scalar but n is a 2D array instead.

[Sal]

I thought that also but I do not believe it is the case. If I enter this code it just doesn't give me the points

function [y,Err,n] = ARCTANA(x)
[rows,columns]=size(x);
y_plot=zeros(rows,columns);
err_plot=zeros(rows,columns);
n_plot=zeros(rows,columns);

for f=1:rows
for g=1:columns
v=x(f,g);
if v<=-1
N=50;

y=(-pi/2);
    for k=0:N
    an=((-1)^k)/((2*k+1)*(v^(2*k+1)));
    y=y-an;
    end
real=atan(v);
Err=abs(real-y);
n=N;

elseif -1<v & v<1
an=v;
y=an;
k=1;
    while abs(an)>1E-12
    an=(((-1)^k)*v^(2*k+1)/(2*k+1));
    y=y+an;
    k=k+1;
    end
real=atan(v);
Err=abs(real-y);
n=k-1;
else
an=1/v;
y=(pi/2);
k=0;

    while abs(an)>1E-12 & k<=50
    an=((-1)^k)/((2*k+1)*(v^(2*k+1)));
    y=y-an;
    k=k+1;
    end
real=atan(v);
Err=abs(real-y);
n=k;
end
y_plot(f,g)=y;
y=y_plot;

err_plot(f,g)=Err;
Err=err_plot;
n=[1 1 1;1 1 1;1 1 1];
end
end

******* GRADING OUTPUT *******
Function name.......CORRECT
       inputs.......CORRECT +1 points
      outputs.......CORRECT +1 points

Calling function [y, Err, n] = ARCTANA(1 x 1 array)
	Grading variable y........correct size +0.5 points
                          ....correct value +0.5 points
	Grading variable Err........correct size +0.5 points
                            ....correct value +0.5 points
	Grading variable n........ERROR: incorrect size
....ERROR

Calling function [y, Err, n] = ARCTANA(3 x 5 array)
	Grading variable y........correct size +0.5 points
                          ....correct value +0.5 points
	Grading variable Err........correct size +0.5 points
                            ....correct value +0.5 points
	Grading variable n........ERROR: incorrect size
....ERROR

Calling function [y, Err, n] = ARCTANA(9 x 7 array)
	Grading variable y........correct size +0.5 points
                          ....correct value +0.5 points
	Grading variable Err........correct size +0.5 points
                            ....correct value +0.5 points
	Grading variable n........ERROR: incorrect size
....ERROR

        HINT: You need to calculate the arctan value with individual elements in the x array.
              How many x array elements are there? How do you indicate each individual element?

Final grade: 8/11

[Voss]

Not a scalar:

n=[1 1 1;1 1 1;1 1 1]

n = 3×3

1 1 1 1 1 1 1 1 1

[Sal]

I understand I am trying to show that the error is not saying that n should be a scalar.

[Voss]

I understand, but "you would get this error if the grading system is expecting n to be a scalar but n is a 2D array instead." Did you try returning a scalar n?

[Walter Roberson]

The grading system contains instructor-written tests for the correctness of variables. The instructor did not think of the possibility that n might not be scalar, and accidentally wrote tests that assume that it is scalar.

[Sal]

Ok seems like something to talk to the proffesor about, thanks.