Hi, friends in math. I have difficulty in evaluating(calculating an approximate value) of the erf(x) integral from 1 to infinity. I know how to do it for the same integral taken from 0 to infinity, but somehow my calculation of the former one does not match the value indicated in the problem book. Please, advise.
Evaluation of the definite integral
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LCKurtz
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For those unfamiliar with erf(x) you should post the integral. You know the value for erf([MATH]\infty[/MATH]), so use
[MATH]\int_1^\infty = \int_0^\infty -\int_0^1[/MATH] and do the second integral numerically. I assume you know a numerical method is necessary.
pka
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LCKurtz
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Admittedly, the OP's post is ambiguous but given the function [MATH]\text{erf}(x) = \frac 2 {\sqrt \pi}\int_0^x e^{-t^2}~dt[/MATH], I think what he is asking for is how to calculate [MATH]\frac 2 {\sqrt \pi}\int_1^\infty e^{-t^2}~dt[/MATH], given that he knows how to calculate [MATH]\frac 2 {\sqrt \pi}\int_0^\infty e^{-t^2}~dt[/MATH]. Perhaps the OP will clarify whether it is actually [MATH]\int_1^\infty \text{erf}(x)~dx[/MATH] that he wants.