/6-1/6)+signum(x-1)*(1/4-(x^2*signum(x))/4)+x^3/6+x^2/4

 (%i6) integrate(signum(x) - signum(1-x),x);
 (%o6) x*signum(x)+(x-1)*signum(x-1)
</pre></td></tr></table>
<p>A plot indicates that indeed (%o5) and (%o6) are continuous at zero and at one.
</p>
<p>For definite integrals with numerical integration limits (including
both minus and plus infinity), the <code>abs_integrate</code> package
converts the integrand to signum form and then it tries to subdivide
the integration region so that the integrand simpl