calculation error in hyperbolic function
2 Ansichten (letzte 30 Tage)
Ältere Kommentare anzeigen
syms x
syms t
U=zeros(1,2,'sym');
A=zeros(1,2,'sym');
B=zeros(1,2,'sym');
C=zeros(1,2,'sym');
series(x,t)=sym(zeros(1,1));
U(1)=(tanh(x))^2
for k=1:3
A(1)=0;
B(1)=0;
C(1)=0;
for i=1:k
A(1)=simplify(A(1)+diff( U(i),x,1)*diff(U(k-i+1),x,1));
B(1)=simplify(simplify(B(1)+U(i)*diff(U(k-i+1),x,2)));
for j=1:i
C(1)=simplify(C(1)+U(j)*U(i-j+1)*diff(U(k-i+1),x,1));
end
end
U(k+1)=(-2*C(1)+(1/2)*B(1)+A(1))/k;
end
for k=1
series(x,t)=(series(x,t)+U(k)*power(t,k-1));
end
series
row=0
C2=zeros(1);
for r=1
row=row+1;
col=0;
e=(r-11)
for t=1
col=col+1;
f=((t)/1000);
C2(row,col)=series(e,f);
end
end
For k=1 the solution is (tanh(x))^2 and using the loop if i evaluate the value for x=-10 the answer is 0.999999999 .But if directly put the value of x=-10 in (tanh(x))^2 the value is -1 .Why this difference appear?
0 Kommentare
Antworten (1)
David Goodmanson
am 23 Nov. 2022
Bearbeitet: David Goodmanson
am 23 Nov. 2022
one possibility:
(tanh(-10))^2
ans = 1.0000 % correct
although
tanh(-(10)^2) % traveling parenthesis
ans = -1
2 Kommentare
David Goodmanson
am 23 Nov. 2022
Bearbeitet: David Goodmanson
am 23 Nov. 2022
Hi yp,
what I meant was, as I understand the problem the first expression (used in the loop) is correct, and the second expression is incorrect. The second expression is a totally different function because the parenthesis is in a different place. I am speculating about what went wrong, and the second expression might not be what you used, but it does have the "correct incorrect answer" of -1.
Siehe auch
Kategorien
Mehr zu Logical finden Sie in Help Center und File Exchange
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!