Hi all,

I'am new to Maple and have some very basic questions. Maple can figure out that the exponential is positive.

> is(exp(x)>0) assuming x::real;
                                     true
But it cannot figure out that a sum of exponentials is positive too:

> is(sum(exp(x*i),i=1..N)>0) assuming x::real,N::integer,N>1;
                                     FAIL

What am I doing wrong? Moreover, what's wrong with this statement:

> is(ln(a+b)-ln(a)=ln(1-b/a)) assuming a::real,b::real,a>0,b>0,b<a;
                                     FAIL

Finally, is there a way to declare a generic fuction f and assume that its image is always a positive real?

Thanks

Nico