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HP Prime bug for approximate(erfc(z)), z as (0+b*i), or erf(b*i)
11-15-2023, 04:53 PM (This post was last modified: 11-15-2023 04:54 PM by Albert Chan.)
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Albert Chan Offline
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RE: HP Prime bug for approximate(erfc(z)), z as (0+b*i), or erf(b*i)
(11-15-2023 04:00 PM)Gil Wrote:  Logically, on HP PRIME, approximate(erf(5*i)) returns
1 -82982738 79.76*i (a complex number with the number 1 as its real part, instead of 0).

Strange.

erf(x) = 2/sqrt(pi) * x * hyp1f1(1/2, 3/2, -x*x)

erf(x)/x = 2/sqrt(pi) * hyp1f1(1/2, 3/2, -x*x)

If x is purely real or imaginery, RHS is real --> LHS is real too.

Without computation, erf(5i) is purely imaginery.
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RE: HP Prime bug for approximate(erfc(z)), z as (0+b*i), or erf(b*i) - Albert Chan - 11-15-2023 04:53 PM



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