atanh returns NaN for values with an absolute value greater than 1
Reported by Calixte DENIZET
BUG DESCRIPTION:
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atanh(3) // NaN in Scilab 6 and 0.3465736 - 1.5707963i in Scilab 5
ERROR LOG:
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HOW TO REPRODUCE THE BUG:
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OTHER INFORMATION:
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