Help with loop error
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My function is as follows but keeps coming up with the error that the output argument "approx" is not assigned. How do I change it to produce the desired outputs?
function [ exact, approx, abs_error, terms ] = calcTaylorTerms( x, dx, tol, max_terms, exp_or_sin )
%CALCTAYLORTERMS
% x: is x
% dx: delta x
% tol: the error tolerance to be met
% max_terms: the maximum number of terms to include before giving up
% exp_or_sin: a flag that determines whether f(x)=e^x or f(x)=sin(x)
% exact: analytical solution to f(x+deltax)
% approx: the Taylor series approximation of f(x+deltax)
% abs_error: the absolute value of the difference between the exact
% solution and the Taylor series approximation
% terms: the number of terms ultimately used in the Taylor series
if isequal(exp_or_sin,"exp")||isequal(exp_or_sin,"sin")
if isequal(exp_or_sin,"exp")
exp_or_sin=exp(x);
elseif isequal(exp_or_sin,"sin")
exp_or_sin=sin(x);
end
abs_error=0;
n=1;
count=0;
terms=1;
while abs_error>=tol && n>1 && terms>max_terms
count=count+1;
terms(count)=exp_or_sin+(1)^(count+1)*(dx^n).*diff(exp_or_sin,x,n)/factorial(n);
approx(count)=sum(terms);
n=n+1;
exact=exp_or_sin(x+dx);
abs_error=abs((exact-approx)/exact);
end
exact=exp_or_sin(x+dx);
approx=approx;
abs_error=abs_error
X=terms;
X(:)=1;
terms=sum(X)
else
exact=NaN;
approx=NaN;
abs_error=NaN;
terms=NaN;
end
end
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回答(1 个)
James Tursa
2017-10-13
编辑:James Tursa
2017-10-13
Maybe move all of the default stuff prior to your if test. E.g.,
exact = NaN;
approx = NaN;
abs_error = NaN;
terms = NaN;
if isequal(exp_or_sin,"exp")||isequal(exp_or_sin,"sin")
:
etc
2 个评论
James Tursa
2017-10-14
If it is coming back as NaN, that gives you a clue. Namely, that these values were not set inside the while loop. Use the debugger to step through your code and figure out why you are not getting inside that while loop.
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