Sine Integral (Not in Base Package)

Evaluates the sine integral for any real number x as defined by si(x) = integral of sin(s)/s between 0 and x. It is si(-x)= -si(x). Details

x is any real number.
si(x) is the result of the calculation of the sine integral for the given value of x.

Sine Integral Details

An efficient algorithm is based on a continued fraction of the combined function

more precisely on

The following diagram shows the graph of the sine integral in the interval (0,15).