Re: Solve problem

*To*: mathgroup at smc.vnet.net*Subject*: [mg98027] Re: [mg97988] Solve problem*From*: Adriano Pascoletti <adriano.pascoletti at dimi.uniud.it>*Date*: Sat, 28 Mar 2009 05:43:06 -0500 (EST)*References*: <200903271035.FAA25199@smc.vnet.net>

In[1]:= a1 /. Cases[{{b1 -> -2, a1 -> -1}, {b1 -> 0.5, a1 -> 3}}, r : (a1 -> (i_)?Positive), Infinity] Out[1]= 3 In[2]:= a1 /. Cases[{{a1 -> 1, b1 -> 3}}, r : (a1 -> (i_)?Positive), Infinity] Out[2]= 1 Adriano Pascoletti 2009/3/27 Bruno Campanini <BC at gmail.com> > I have a Solve[...] which gives me solutions like > {{b1 -> -2, a1 -> -1 }, {b1 -> 0.5, a1 -> 3}} > or like > {{a1 -> 1, b1 -> 3}} > > How can I get the positive value for a1, which is 3 > in the first case and 1 in the second one? > > Bruno > >

**References**:**Solve problem***From:*"Bruno Campanini" <BC@gmail.com>