# problem with f surf

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yogeshwari patel on 12 Jun 2021
f1 = @(x,t) 0.7*(1-tanh((0.7/2)*((x)-0.7*(t))))
syms x n
syms t
U=zeros(1,2,'sym');
A=zeros(1,2,'sym');
B=zeros(1,2,'sym');
series(x,t)=sym(zeros(1,1));
U(1)=0.7*(1-tanh((0.7/2)*x))
for k=1:3
A(1)=0;
for i=1:k
A(1)=A(1)+U(i)*U(k-i+1) ;
end
B(1)=0;
U(k+1)=(((diff(U(k),x,2)-A(1)))/k);
end
disp (U)
for k=1:4
series(x,t)=simplify(series(x,t)+U(k)*(power(t,k-1)));
end
% f2=series
f3=@(x,t) series
fsurf(f1,[-5 0 -5 5])
fsurf(f3,[-5 0 -5 5])
fsurf(f1-f3,[-5 0 -5 5])
The graph is not displayed

Sulaymon Eshkabilov on 12 Jun 2021
THere are a few errs in your code - loop calculations and redefining 'f3'. Here is the corrected code:
...
series=0;
for k=1:4
series=series+(U(k).*(power(t,k-1)));
end
f3= series;
figure(1)
fsurf(f1,[-5 0 -5 5])
figure(2)
fsurf(f3,[-5 0 -5 5])
figure(3)
fsurf(f1-f3,[-5 0 -5 5])
##### 2 CommentsShowHide 1 older comment
Sulaymon Eshkabilov on 12 Jun 2021
Most Welcome!

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