Re: Integer designation
- To: mathgroup@smc.vnet.net
- Subject: [mg11780] Re: [mg11754] Integer designation
- From: Sean Ross <seanross@worldnet.att.net>
- Date: Sat, 28 Mar 1998 00:25:17 -0500
- References: <199803260809.DAA06295@smc.vnet.net.>
blimbaum_jerry@ccmail.ncsc.navy.mil wrote: > > I want to re-ask a question I asked before about designating a > variable as an integer. On page 261 of the 3rd edition of > Mathematica > it talks about making an integer assignment, i.e. "f[n_Integer] is > like defining a function f that must take an argument of "type" > Integer. I try this in a function like f[x_,n_Integer]:=Sin[n Pi > (x/a)] and then type f[a,n] and expect the answer zero but it just > gives me Sin[n Pi]. What have I misunderstood here? > > thanks. Jerry Blimbaum US Navy Lab, Panama City, Florida > > > Long Live MathGroup f[x_Integer] merely says that this function is only defined if x is an integer. If you insert a real number for that argument, there is no definition. There is no "data typing" in mathematica. As far as I know, there is absolutely no way to tell mathematica that a certain symbol is an integer of unspecified value. The only function that has some of this kind of functionality in it is Integrate which has an Assumptions option. Also, f[x_,n_Integer]:=Sin[n Pi(x/a)] f[a,n] should have returned f[a,n] not Sin[n Pi] I suspect that there were other definitions operating in your session, perhaps from previous versions of the symbol f. In general, it is good programming practice to Clear the definition of a symbol before every function definition, as in: Clear[f] f[x_,n_Integer]:=Sin[n Pi(x/a)] f[a,n] Remember that mathematica loads definitions and rules into the kernel in the order of execution from the start of the session to the end. You can delete every cell in the notebook or even close the notebook and start a new one and you have not affected the definitions in the kernel one bit. If you enter a definition for f[x_,n_], that does not affect previous definitions for f[x_Real,n_Complex], f[x_,n_Integer] etc. They all exist simultaneously. -- Remove the _nospam_ in the return address to respond.
- References:
- Integer designation
- From: blimbaum_jerry@ccmail.ncsc.navy.mil
- Integer designation