josdejong/mathjs

cot reports wrong value for (0, 0)

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#1,427 opened on Mar 2, 2019

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Description

b = math.complex(0,0) then b.cot() reports (NaN, NaN) as compared to Mathematica's ComplexInfinity. Not that the correct answere is always useful, but it (the NaN answer) did cause a problem in testing extended precision complex functions.

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Research direction
Investigate the cot function for complex numbers in mathjs. Trace the implementation to understand how it computes cot for Complex objects. For the case where both real and imaginary parts are zero, the result should be infinity (ComplexInfinity) rather than NaN. Look at the formula: cot(z) = cos(z)/sin(z). At z=0, sin(0)=0, so cot(0) is infinite. Check if there is a special case handling and fix it.
Tech stack
javascript
Domain
api
Issue type
Bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
2
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
1-3 hours
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
Active
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
Clear
Prerequisites
JavaScriptComplex numbers
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
70