\[ \int \text {Si}(b x) \, dx \]
Optimal antiderivative \[ \frac {\cos \left (b x \right )}{b}+x \sinIntegral \left (b x \right ) \]
command
integrate(sin_integral(b*x),x, algorithm="fricas")
Fricas 1.3.8 (sbcl 2.2.11.debian) via sagemath 9.6 output
\[ \frac {b x \operatorname {Si}\left (b x\right ) + \cos \left (b x\right )}{b} \]
Fricas 1.3.7 via sagemath 9.3 output
\[ {\rm integral}\left (\operatorname {Si}\left (b x\right ), x\right ) \]