Problem 837. Find all the zeros of sinus , cosinus and tangent in a given interval

Created by Aurelien Queffurust

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The aim is to find all the zeros of a function within an interval.
Input :
fcn : an anonymous function (@sin, @cos...)
lb : lower bound
ub :upper bound
Output :
output : vector with unique values for which the input function return zeroThe values must be sorted in ascending order.
Example
output = find_zeros(@sin,0,2*pi) will return :
output = [0.0000    3.1416    6.2832]
since the sinus function between [0 2pi] is zero for [0 pi 2pi]

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Last Solution submitted on Jul 09, 2024

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5 Comments

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Tim on 17 Jul 2012

I think test case 2 might be incorrect.

Richard Zapor on 17 Jul 2012

I disagree slightly with the expected solution to test 2.
Test 2 cos between [0 2pi]
[-pi/2 pi/2 3*pi/2]

I do not believe that -pi/2 is in the interval [0 2*pi].

If -pi/2 is desired then the answer to sin [0 2*pi] should be [-2*pi -pi 0 pi 2*pi]

Richard Zapor on 17 Jul 2012

Correction of assert function.
One of the ")" is in the wrong place.
is:
assert(all(abs(find_zeros(@sin,0,2*pi) -[0 pi 2*pi]<1e-9)))

Should be:
assert(all(abs(find_zeros(@sin,0,2*pi) -[0 pi 2*pi])<1e-9))

Rafael S.T. Vieira on 4 Sep 2020

As mentioned by others, the 2nd test case is incorrect, -pi/2 is outside the interal [0,2*pi] for the function cosine. And if we do plot cos(x) on said interval, we notice that the cosine function crosses the x-axis only twice.

goc3 on 29 Sep 2020

The –pi/2 has been removed from that test case.

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Problem 837. Find all the zeros of sinus , cosinus and tangent in a given interval

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Problem 837. Find all the zeros of sinus , cosinus and tangent in a given interval

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