FUNCTION: wnn - test a unit form for weak non-negativity

CALLING SEQUENCE:
wnn(q)
wnn(q,rt)

PARAMETERS:
q - a unit form
rt - an optional parameter evaluating to a name

SYNOPSIS:

• wnn uses a program of Hans von Hoehne to test, whether the unit form q given as first argument is weakly non-negative.

• If q is weakly non-negative, the function will return the value 'true', otherwise the value 'false'.

• If q is weakly non-negative, the second argument rt, if given, will be assigned a list of the critical vectors of q.

• If q is not weakly non-negative, the second argument rt, if given, will be assigned a single positive vector on which the form q is negative.

EXAMPLES:

> a:=[5,[[1,2,3,4,5]]];

> q:=titsform(a);

> wnn(q,'rt');

> print(rt);

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> a:=hypercritical_algd(4,1);

> q:=titsform(a);

> wnn(q,'rt');

> print(rt);

> 1/2*innerprod(rt,q,rt);