What is the integral of e^(2x^2)?

1 Answer
Aug 3, 2015

int e^(2x^2) dx cannot be expressed using elementary functions. You need the imaginary error function, erfi(x).

Explanation:

The imaginary error function is 2/sqrtpi int e^(x^2) dx

int e^(2x^2) dx can be intergrated using substitution u = sqrt2 x so du = sqrt2 dx and we get:

int e^(2x^2) dx = 1/sqrt2 int e^(u^2) du

= 1/sqrt2 sqrtpi/2 "erfi" u +C

= sqrt(2pi)/4 "erfi"(sqrt2x) +C