Re: Simple Problem (I suppose...)

*To*: mathgroup at smc.vnet.net*Subject*: [mg22220] Re: Simple Problem (I suppose...)*From*: Tobias Oed <tobias at physics.odu.edu>*Date*: Fri, 18 Feb 2000 02:35:03 -0500 (EST)*Organization*: Old Dominion University*References*: <888a2i$c6a@smc.vnet.net>*Sender*: owner-wri-mathgroup at wolfram.com

Andreas Kallmeyer wrote: > > Hi! > > I just got Mathematica 4 and when I try such easy calculations as below > and then I can't plot the result.... WHY?? I really have no clue. > > Thanks, > > Andreas. > > Here my text is clipped: > " > In[1]:= > Remove["Global'*"] ^ wrong quote, you want ` instead of ' > > Remove::"rmnsm": "There are no symbols matching \"\!\(\"Global'*\"\)\"." > > In[2]:= > \!\(f[\(x\_-\)] := \ x\^5 + x\^4 + x\^2\) Try ??f, you will see f[SubMinus[x]] := x^5 + x^4 + x^2 and I have the feeling you want, f[x_]:=x^5 + x^4 + x^2 so just type this in, skip the escapes! It seems to me that you have all this clutter because you use Mathematica through the front end. If you want to master Mathematica forget about the front end for a moment, and use the terminal like interface to the kernel. > > In[3]:= > Plot[f[x], {x, -10, 10}]; this works now > > Plot::"plnr": "\!\(f[x]\) is not a machine-size real number at \!\(x\) = > \ > \!\(-9.999999166666667`\)." > > Plot::"plnr": "\!\(f[x]\) is not a machine-size real number at \!\(x\) = > \ > \!\(-9.188660168541684`\)." > > In[4]:= > \!\(f2[\(x\_-\)]\ = \ \[PartialD]\_x f[x]\) > I use f2[x_]:=Evaluate[D[f[x],x]] and get 2 x + 4 x^3 + 5 x^4 which is probably what you want Tobias.