função de erro complementar
y = erfc(x)
real vector or matrix
real vector or matrix (of same size than x)
erfc computa a função de erro complementar:
erfc
/+oo 2 2 | -t y = ------- | e dt sqrt(pi) | /x y = 1 - erf(x)
erf([0.5,0.2])+erfc([0.5,0.2])