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7.3.12  Complementary error function

The complementary error function is defined by

  erfc(x)=
2
√
π
∫
+∞


x
e−t2dt=1−erf(x).

Hence erfc(0)=1, since

  ∫
+∞


0
e−t2dt=
√
π
2
.

The erfc command computes the complementary error function.

Examples

erfc(1)
     
1−erf⎛
⎝
1⎞
⎠
          
1-erfc(1/(sqrt(2)))*0.5
     
0.841344746069           
Remark.

The relation between erfc and normal_cdf (see Section 20.4.7) is:

  normal_cdf(x) =1−
1
2
erfc⎛
⎜
⎜
⎜
⎜
⎝
x
√
2
⎞
⎟
⎟
⎟
⎟
⎠
.

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