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The obsolete info, which have to be removed after estimated

a divergent integral, can be kicked out by "IS" oporator:

(%i1) integrate(EXP(-la*t)*la,t,0,INF);

Is la positive, negative, or zero?

n;

Integral is divergent

-- an error. Quitting. To debug this try DEBUGMODE(TRUE);

(%i2) integrate(EXP(-la*t)*la,t,0,INF);

Integral is divergent

-- an error. Quitting. To debug this try DEBUGMODE(TRUE);

HOW DOES IT KNOW ?

(%i3) is(la<0);

MACSYMA was unable to evaluate the predicate:

la < 0

-- an error. Quitting. To debug this try DEBUGMODE(TRUE);

(%i4) integrate(EXP(-la*t)*la,t,0,INF);

Integral is divergent

-- an error. Quitting. To debug this try DEBUGMODE(TRUE);

HOW DOES IT KNOW ?

(%i5) is(la>0);

MACSYMA was unable to evaluate the predicate:

la > 0

-- an error. Quitting. To debug this try DEBUGMODE(TRUE);

(%i6) integrate(EXP(-la*t)*la,t,0,INF);

Integral is divergent

-- an error. Quitting. To debug this try DEBUGMODE(TRUE);

HOW DOES IT KNOW ?

(%i7) is(la=0);

(%o7) FALSE

NOW THE INFO IS KICKED OUT

(%i8) integrate(EXP(-la*t)*la,t,0,INF);

Is la positive, negative, or zero?

p;

(%o8) 1