MaplePrimes - answers and comments on Question, Can I set a default for assume ?

RealDomain

Joe Riel — Fri, 16 Nov 2012 10:10:57 Z

There is the ?RealDomain package, which might be useful. However, it doesn't assume variables are positive, just real. And it doesn't work with the assume facility.

assuming real or positive

Alejandro Jakubi — Fri, 16 Nov 2012 11:31:24 Z

For this purpose, assuming is most convenient, see ?assuming,details for examples of ... assuming real or ... assuming positive constructs. Be aware though that some commands have not been adapted yet to the usage of this syntax.

maybe a little relief

acer — Fri, 16 Nov 2012 12:04:38 Z

Programming it in a loop or sequence might give a little relief.

restart:

for var in [x,y,z,p] do assume(var>=0); end do:

assume(w<0);

is( x+y+z+p >= 0 );

                              true

is( (x+y+z+p)*w <= 0 );

                              true

acer

The combination will do the trick

awehring — Fri, 16 Nov 2012 18:32:59 Z

Thanks a lot, to all of you !

I think I will live very well with a combination of your tricks:

with(RealDomain) at the beginning of the document to cover most issues and assuming or assume where necessary. The loop is convenient too.

:-)

BTW (before someone struggles here), there is an issue, if you combine alias and assume, as assume renames your variables (x becomes x~).

E.g.

alias(`x*`=xs) # (x* marked as Atomic Identifier)

xs+1 is (correctly) shown as x*+1

assume(xs >=0)

xs+2 is shown as xs~+2

interface(showassumed=0) # suppresses ~ for variables with assumptions

xs+3 is shown as xs+3

But assuming works fine (but of course just for the statement, where you set it).