Cube roots of negative numbers
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David Wishart
Jun 1, 2021, 8:30:43 AM6/1/21
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I'm getting strange results when trying to take the cube root of a negative numbers, test case below.
When I use root(negative_number,3) Numbas appears to be returning the first complex root
root(-1,3) = 0.5 + 0.86i when I would only be interested in the real one eg -1.
Is there any reason why this could only have happened recently? I ask as the full question I have is part of SCORM test that has deployed without this issue for 4 years. Whilst there is only a 1.4% chance of the question returning a negative to deal with, I'd estimate that in the region of 1000 students could have attempted this question over that period but errors have only surfaced in the last month.
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