Unrecognized function or variable 'x'.

function y = Tsin(x,n)
x=input('Degrees: ');
y=input('Terms: ');
%Tsin calculates the sin using Taylor formula.
%Input arguments:
%x The angle in degrees, n number of terms.
z=x*pi/180;
y=0;
for k=0:n-1
    y=y+(-1)^k*z^(2*k+1)/factorial(2*k+1);
end

RUN then

>> Tsin(x, n)
Unrecognized function or variable 'x'.

[Tommy]

When you run

>> Tsin(x,n)

you need to provide values for both x and n. However, it looks like you are obtaining x within the function via this line:

x=input('Degrees: ');

If so, you do not need to supply x to your function. I would recommend changing the function definition to match

function y = Tsin(n)

and then calling

>> Tsin(n)

for whatever n value you want.

[Emre Can Usengul]

I want to ask to users degrees and terms. if on workspace values for x and n the code is run but give it same result which number ı type.

[Adam Danz]

There are lots of ways to ask users for input.

https://www.mathworks.com/help/matlab/ref/inputdlg.html

https://www.mathworks.com/help/matlab/ref/input.html

etc...

[Nandini]

PenaltyFactor=100;
LMUpdateRate=0.0100;
AbsoluteTolerance=5.0000e-06;
RelativeTolerance=0.0050;
MaxIterations=1000;
InitialIMFs=zeros(length(x),5);
InitialLM=zeros(length(x)+1,1);
CentralFrequencies= [];
InitializeMethod='peaks';
FFTLength=2*length(x);
NumIMFs= 5;
SignalLength= length(x);
HalfSignalLength=length(x)/2;
MirroredSignalLength=2*length(x);
DataType= 'double';
NumHalfFreqSamples= length(x)+1;
Display= 0;
%%
nfft = FFTLength;
penaltyFactor = PenaltyFactor;
numIMFs = NumIMFs;
relativeDiff = inf;
absoluteDiff = relativeDiff;
tau = LMUpdateRate; % Lagrange multiplier update rate
xr = [x(HalfSignalLength:-1:1); x; x(SignalLength:-1:ceil(SignalLength/2)+1)];
y = fft(xr,FFTLength);
sigFDFull = y; 
% Get half of the bandwidth
sigFD = sigFDFull(1:NumHalfFreqSamples);
initIMFfdFull = fft(InitialIMFs,nfft);
initIMFfd = initIMFfdFull(1:NumHalfFreqSamples,:) + eps; 
IMFfd = initIMFfd;
sumIMF = sum(IMFfd,2);
LM = InitialLM(:); % Lagrange Multiplier
%% Frequency vector from [0,0.5) for odd nfft and [0,0.5] for even nfft
f = (0:(nfft/2))/nfft;
%%  Get the initial central frequencies
x=abs(sigFD);
BW = 2/FFTLength; % bandwidth of signal
minBWGapIndex = 2*BW/f(2);
x(x<mean(x)) = mean(x);
TF = islocalmax(x,'MinSeparation',minBWGapIndex);
pkst = x(TF);
locst = f(TF);
numpPeaks = length(pkst);
% Check for DC component
if x(1) >= x(2)
    pks = zeros(numpPeaks+1,1);
    locs = pks;
    pks(2:length(pkst)+1) = pkst;
    locs(2:length(pkst)+1) = locst;
    pks(1) = x(1);
    locs(1) = f(1);
else
    pks = zeros(numpPeaks,1);
    locs = pks;
    pks(1:length(pkst)) = pkst;
    locs(1:length(pkst)) = locst;
end   
[~,index] = sort(pks,'descend');
centralFreq = 0.5*rand(NumIMFs,1);

% Check if the number of peaks is less than number of IMFs
if length(locs) < NumIMFs
    centralFreq(1:length(locs(index))) = locs;
else
    centralFreq(1:NumIMFs) = locs(index(1:NumIMFs));
end

%%
iter = 0;
f=f';

initIMFNorm = abs(initIMFfd).^2;
normIMF = zeros(size(initIMFfd,1),size(initIMFfd,2));
while (iter < MaxIterations && (relativeDiff > RelativeTolerance ||...
        absoluteDiff > AbsoluteTolerance))   
    for kk = 1:numIMFs
        sumIMF = sumIMF - IMFfd(:,kk);          
        IMFfd(:,kk) = (sigFD - sumIMF + LM/2)./...
            (1+penaltyFactor*(f - centralFreq(kk)).^2);
        normIMF(:,kk) = abs(IMFfd(:,kk)).^2;
        centralFreq(kk) = (f.'*normIMF(:,kk))/sum(normIMF(:,kk));           
        sumIMF = sumIMF + IMFfd(:,kk);            
    end
    LM = LM + tau*(sigFD-sumIMF);
    absDiff = mean(abs(IMFfd-initIMFfd).^2);
    absoluteDiff = sum(absDiff);
    relativeDiff = sum(absDiff./mean(initIMFNorm));
    
    % Sort IMF and central frequecies in descend order
    % In ADMM, the IMF with greater power will be substracted first
    [~,sortedIndex] = sort(sum(abs(IMFfd).^2),'descend');
    IMFfd = IMFfd(:,sortedIndex);
    centralFreq = centralFreq(sortedIndex(1:length(centralFreq)));
    initIMFfd = IMFfd;
    initIMFNorm = normIMF;  
    iter = iter + 1;
    
end

%%--------------------- Step 08 --------------------------------

%% Convert to time domain signal     
% Transform to time domain
IMFfdFull = complex(zeros(nfft,numIMFs));
IMFfdFull(1:size(IMFfd,1),:) = IMFfd;
if ~mod(FFTLength,2)
    IMFfdFull(size(IMFfd,1)+1:end,:) = conj(IMFfd(end-1:-1:2,:));
else
    IMFfdFull(size(IMFfd,1)+1:end,:) = conj(IMFfd(end:-1:2,:));
end
[~,index] = sort(centralFreq,'descend');   
%%
z=IMFfdFull(:,index);
xr = real(ifft(z,FFTLength));
IMFs_without_inbuild = xr(HalfSignalLength+1:MirroredSignalLength-HalfSignalLength,:);
residual_without_inbuild = PPGblr1 - sum(IMFs_without_inbuild,2);

[Adam Danz]

@Patrick's answer moved here as a comment

-----------------------------------------------------------------

function Simpson1 (f1,a,b,M)
%F es el integrando como una cadena de caracteres
f=inline(f1);
h=(b-a)/(2*M);
s1=0;
s2=0;
for k=1:M
    x=a+h*(2*k-1);
    s1=s1+feval(f,x);
end
for k=1:M-1
    x=a+h*2*k;
    s2=s2+feval(f,x);
end
s=(h/3)*(feval(f,a)+feval(f,b)+4*s1+2*s2);
syms x
sv=int (f(x),a,b);
error=eval(abs(s-sv)*/abs(sv))*100;
disp('rpta simpson error true%')
fprintf('/t%0.5f/t%0.5f/n',s,error);
end

Console

Simpson1((9.8*67/12.5)*(1-exp(-12.5*x/67)),0,8,10)

Unrecognized function or variable 'x'.

[Adam Danz]

@Patrick The error message tells you which variable is causing the problem: "x".

When you call the function using

Simpson1((9.8*67/12.5)*(1-exp(-12.5*x/67)),0,8,10)
%                                   ^

the variable x is not defined.

[Diwitha]

clear all

sym x

f(x)=x^ 4+2*x^ 3-8*x^ 2

[Diwitha]

It says Unrecognized function or variable 'x'.

[Juan David]

% Función para calcular el valor de Lagrange

function y = lagrange2(X, Y)
n=length(X);
sym x;
for i=1:n
    w=1;
    for j=1:n
        if j~=1
           w = w * (x - X(j)) / (X(i) - X(j));

        end
    end
  

end

 y = 0;
for i=1:n
    y = y + w(i) * Y(i);
end

y=simplify(expand(ecuacion));

end


RUN then

Unrecognized function or variable 'x'.

Error in lagrange2 (line 10)
           w = w * (x - X(j)) / (X(i) - X(j));
 

[Voss]

Instead of

sym x;

use

syms x;

or

x = sym('x');

Answer 1

[Adam Danz]

You need to define the input variables. You cannot simply run a function that has undefined input variables.

x = 45
n = 8
Tsin(x,n)

____________________________________

Copy of question:

function y = Tsin(x,n)
x=input('Degrees: ');
y=input('Terms: ');
%Tsin calculates the sin using Taylor formula.
%Input arguments:
%x The angle in degrees, n number of terms.
z=x*pi/180;
y=0;
for k=0:n-1
    y=y+(-1)^k*z^(2*k+1)/factorial(2*k+1);
end

RUN then

>> Tsin(x, n)
Unrecognized function or variable 'x'.

[Dylan Radey]

can't define a variable for fiding a root :\

[Adam Danz]

@Dylan Radey I don't know what that means. All variables are defined either directly by the user or from computations within the function/script.

Answer 2

[Yuyang Mao]

I got the same problem before.

Explaination: Please make sure that you have add your function to the path!

solution:

• Click run, it jumps out a window
• click 'add to path', is shows error in red color which is fine
• now give the name of your function again, in your case is 'Tsin(x,n)'

And this should work.

Best,

Yuyang

[Adam Danz]

Good advice. However, in this question, the function name is Tsin but the unrecognized variable name is x.

[Jordan Wood]

Need to reinput the values you want for x and n in the command window

Answer 3

[SUNIL KUMAR]

syms x
solve('x+3=4',x)

Error using sym/solve>getEqns (line 418)
List of equations must not be empty.

Error in sym/solve (line 226)
[eqns,vars,options] = getEqns(varargin{:});

Answer 4

[SUNIL KUMAR]

f=inline('x^2','x')

f =

     Inline function:
     f(x) = x^2

diff(f(x),x)

Unrecognized function or variable 'x'.

[Stephen23]

syms x
f = x^2
diff(f,x)