Undefined function 'equation' for input arguments of type 'double'
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I want to write a function equation(M,epsilon,tol) which sets the solution of with an approximation error . So I have:
function x=newtonp(f, x, tol, h)
if nargin<4
h=1e-8
end
if nargin<3
tol=1e-8
end
while abs(f(x))>tol
g=(f(x+h)-f(x))/h
x=x-f(x)/g
end
end
function y=equation(M,epsilon,tol)
y=M+epsilon*sin(x)-x
end
Then I write:
newtonp(@equation(x),x, tol, h)
However I get
Undefined function 'equation' for input arguments of type 'double'
Can anyone correct my code?
10 Comments
per isakson
on 8 Apr 2020
Edited: per isakson
on 8 Apr 2020
Is this the first time you use Grader?
Why did you write the function called newtonp ?
Answers (1)
per isakson
on 8 Apr 2020
Edited: per isakson
on 8 Apr 2020
This is my guess
function x = equation( M, epsilon, tol )
h = 1e-8;
x = pi/6; % first guess
foo = @(x) M+epsilon*sin(x)-x;
while abs(foo(x))>tol
g=(foo(x+h)-foo(x))/h;
x=x-foo(x)/g;
end
end
Try it
y = equation(0.5,0.5,1e-8)
y =
0.88786
And why the second input is called epsilon is a mystery to me!
4 Comments
per isakson
on 9 Apr 2020
Edited: per isakson
on 9 Apr 2020
What's the meaning of "Variable count has an incorrect value." ? Could it refer to the number of variables in the function? No!
Speculation:
- Modify the sentence to "The variable, count, has an incorrect value." (It's not your English teacher who wrote that sentence.)
- There is a variable named count in the program that evaluates the submission
- count is used to keep track of the number of iterations
- implementations of numerical methods shall be efficient (among other requirements)
- "our" function, equation, might fail an efficiency test. Too many iterations. How did you chose the step value?
- Furthermore, in each iteration the function, foo, is evaluated three times for the same value of x. Maybe, count is the number of evaluations of foo().
Your turn!
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