dont know what is that error in the last three lines

f=@ () cos(x) +1/(1+x^2 ); %%Given function f(x)
fd=@(x) -sin(x)-2*x/(1+x^2); %%Derivative of the function f'(x) 
root=Newton cap Raphson(f,fd,1.5,0.05,1 10); %Function call to compute the root of the function with guess 1.5 and specified error and tolerance 
function Xs = NewtonRaphson(Fun, under, Xo ,Err,imax) %%Function which implements Newton Raphson Method 
disp('Values in each iteration:' ) 
for(i = 1:max) %%Runs a loop from 1 to maximum iterations 
Xi=Xo -Fun(Xo )/Funder(Xo ) ; %%NR method updating scheme 
disp(Xi) %Display current root 
if (abs((Xi-Xo)/Xo)<Err) %%lf error is less break 
Xs = Xi ; 
break 
end 
Xo=Xi; %%Update 
end 
if(i==imax) %%lf maximum iteration reached 
fprintf('Solution not obtained in %i iterations',imax) 
Xs=( 'No Answer' ); 
end 
end

??? root=Newton cap Raphson(f,fd,1.5,0.05,1 10); %Function call to compute the root of the function with guess 1.5 and specified error and tolerance 
                |
Error: Unexpected MATLAB expression.

[Walter Roberson]

No MATLAB function can be named with spaces in it. You cannot create a function named Newton cap Raphson complete with spaces.

[dpb]

root=Newton cap Raphson(f,fd,1.5,0.05,1 10);

is invalid syntax.

You've got blanks in a command line and the word "cap" where undoubtedly meant

root=NewtonRaphson(f,fd,1.5,0.05,1 10);

[Radwan Alerqsousi]

well, thanks alot the error has gone one more quistion tho

Error: File: aya.m Line: 5 Column: 1

Function definitions are not permitted at the prompt or in scripts.

any clue what is this ?

[dpb]

Exactly what is says it is -- you can't define a function at the command line or (prior to a pretty recent release altho I don't recall which one) in a script m-file.

Functions can only be defined in an m-file of the same name in that case. So your function would be saved in a disk file named NewtonRaphson.m