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Purpose
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nag_erf (s15aec) returns the value of the error function,  .
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Description
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nag_erf (s15aec) evaluates
![erfx=2/(sqrt(Pi))(∫)[0]^xe^(-t^2)dt](/support/helpjp/helpview.aspx?si=9672/file08645/math43.png)
The approximation is based on Chebyshev expansions.
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Error Indicators and Warnings
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Accuracy
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On a machine with approximately 11 significant figures the function agrees with available tables to 10 figures and consistency checking with s15adc (nag_erfc) of the relation  shows errors in at worst the 11th figure.
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