Re: How to force numeric output

*To*: mathgroup at smc.vnet.net*Subject*: [mg115658] Re: How to force numeric output*From*: Peter Pein <petsie at dordos.net>*Date*: Mon, 17 Jan 2011 05:41:59 -0500 (EST)*References*: <igrqb1$qmq$1@smc.vnet.net> <iguirf$8tl$1@smc.vnet.net>

On 16.01.2011 11:55, KenR wrote: > On Jan 15, 4:45 am, KenR<ramsey2... at msn.com> wrote: >> I am new to Mathematica and cant seem to get it to give a numeric >> answer to >> >> input y = 5; x = floor[sqrt[y+1.0]]; x. >> >> instead of a numeric it gives "out floor[sqrt[6.0]]" >> >> what am I doing wrong? >> >> I have Mathematica 8.0 >> >> Thankyou, Kenneth Ramsey > > I was looking at past posts and came upon a similar situation. Thanks > to those who e-mail me I am aware that the functions Floor and Sqrt > must be capitalized. It still apparently will not work because > Mathematica does not know whether a positive or negative answer is > desired. > > A similar situation was posted below where the sqrt of meter^2 etc was > desired. A reader responded to write the code "Assuming[ > {Positive[Meter], Positive[Second]}, > Refine[(Sqrt[Meter^2/Second^2] Second)/Meter^2] > > How would I invoke a similar solution to my case? > Sorry, this does not make sense to me. You've got y=5 and z in z=Sqrt[y+1] is defined to be the positive solution of x^2=6 (in this case). So there are no assumption needed. Maybe I misunderstand your question :( Do you want both values Floor[+/-Sqrt[6]]? With[{y = 5}, x = Floor[z] /. Solve[z^2 == 1 + y, z] ] will assign {-3,2} to x Peter