From: Rainer Schöpf <rainer.schoepf@gm...>  20110721 22:01:34

Hi everybody, I've just checked in two patches to the integrator (files driver.red and isolve.red) that are supposed to solve some problems in conjunction with algint. algint uses the fluid intvar to store the integration variable, but the standard integrator didn't always update this when it performs a substitution before calling algint. (I would appreciate if someone would look over these patches.) In particular, this improves the result for the integral of 1/(sqrt(dx)*sqrt(cx)*sqrt(bx)*sqrt(ax)*(a*ba*xb*x+x**2)); as reported in http://sourceforge.net/tracker/?func=detail&aid=2507063&group_id=248416&atid=1126256 Note: run it with "on ezgcd", otherwise it takes at least 10 times as long to compute. You still get the "Zero divisor" error messages, though. Another example that went very wrong is load_package algint; on ezgcd; on algint; on factor; kk := 1/(sqrt((ax)*(bx)*(x1)*x)); ll:=kk/(x*(a*b*x  a*b  a*x**2 + a*x  b*x**2 + b*x + x**3  x**2)); sauvetasoeur:=int(ll,x); verif:=df(sauvetasoeur,x)ll; This one gives the correct result only when precise is off, and the final result with precise on suggests to me that there is a problem with a sign of a sqrt term. Rainer 