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#### Re: Chained-functional notation examples?

```On 5/6/14 at 2:26 AM, dog@gmail.com (Unknown) wrote:

>I came to 'Mathematica' via Xahlee's criticism of the ad-hoc nature
>of unix-piping [functional notation].  He claims [& I believe him]
>that Mathematica has a better, more consistent notation.  But the
>facility of PRE, IN & POST-fix alternatives, seems bad.  You want
>ONE way of acieving the goal. More rules just increases mental load.

If you are looking for a system with one way to achieve a given
goal, Mathematica isn't it. There are multiple ways of achieving
a result without using different notations. For example,
consider how you might find the sum of the first n integers. All
of the following will work:

limit = 10^6;
For[sum = 0; n = 1, n <= 10, n++, sum += n]; sum

Plus@@Range[limit]

Total[Range@limit]

Sum[n,{n,m}]/.m->limit

Intelligent use of pre-, post- and in-fix notations generally
makes Mathematica code easier to read/understand. For example, I
could have written

Total[Range@limit] as

Total[Range[limit]]

but fewer levels of [] makes it easier from my perspective to read.

>Just as a test, how would Mathematica handle the following [or part

>search all files in Dir=tree D |
>which are less than N days-old | and which contain string S1 | and
>which contain string S2 .

SetDirectory[dirname];
Cases[FileNames[],
(FileType[#]===File &&
StringCases[#, s1]!={} &&
StringCases[#, s2]!={} &&
(Subtract@@(AbsoluteTime /@ {Date[][[;; 3]], FileDate[#][[;; 3]]}/86400)<age)&]

No need to pipe results from one operation to the next. And the
above syntax is platform neutral.

>Try: Search in table of ListOfOpenFiles for lineS with path-P
>[field] | which have same tty-field as line with path-P2 & program-M [field]

Less clear here to me what it is you are looking for, but
FindList is probably the right function.

``` 0  Bill
5/7/2014 6:44:45 AM comp.soft-sys.math.mathematica  28821 articles. 0 followers. 0 Replies 638 Views Similar Articles

[PageSpeed] 13 Similar Artilces:

Re: Chained-functional notation examples? #5
On 5/7/14 at 2:44 AM, dog@gmail.com (Unknown) wrote: >Here's a related real-live problem: >list all files in Dir-tree:D | which are less-than daysOld:N | and >contain "egal" in the FullPathName | and contain String:"uid" OR >"UID" It is not entirely clear what it is you are trying to do. There are a couple of ways to obtain a list of files in a given directory. First, if the directory is the current working directory, then FileName[] will return a list of every thing at the top level of the directory. But in this case, only the...

Re: Chained-functional notation examples? #4
A query such as this might do what you have in mind. Here directoryname should be changed to whatever directory you want searched. Select[FileNames[("*uid*" | "*UID*"), directoryname, Infinity], ((StringMatchQ[DirectoryName[#] , "*egal*"] && Today < DayPlus[FileDate[#], 3]) &] Also there is a case sensitive switch if you want to allow strings with e.g. "uID". If you want to allow that uid only in the name and not full string Daniel Lichtblau Wolfram Research ------------------- On Tue, 06 May 2014 06:26:46 +0...

Re: Chained-functional notation examples? #3
A query such as this might do what you have in mind. Here directoryname should be changed to whatever directory you want searched. Select[FileNames[("*uid*" | "*UID*"), directoryname, Infinity], ((StringMatchQ[DirectoryName[#] , "*egal*"] && Today < DayPlus[FileDate[#], 3]) &] Also there is a case sensitive switch if you want to allow strings with e.g. "uID". If you want to allow that uid only in the name and not full string Daniel Lichtblau Wolfram Research ------------------- On Tue, 06 May 2014 06:26:46 +0...

Re: Chained-functional notation examples? #2
A query such as this might do what you have in mind. Here directoryname should be changed to whatever directory you want searched. Select[FileNames[("*uid*" | "*UID*"), directoryname, Infinity], ((StringMatchQ[DirectoryName[#] , "*egal*"] && Today < DayPlus[FileDate[#], 3]) &] Also there is a case sensitive switch if you want to allow strings with e.g. "uID". If you want to allow that uid only in the name and not full string Daniel Lichtblau Wolfram Research ------------------- On Tue, 06 May 2014 06:26:46 +0...

Chained-functional notation examples?
I came to 'Mathematica' via Xahlee's criticism of the ad-hoc nature of unix-piping [functional notation]. He claims [& I believe him] that Mathematica has a better, more consistent notation. But the facility of PRE, IN & POST-fix alternatives, seems bad. You want ONE way of acieving the goal. More rules just increases mental load. A major benefit of functional [unix-piping] programming style, is that you don't need to remember the-full-journey: you just need to remember the previous stage's output. Nor do you need to remember several names: the previous outp...

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Re: Novice problem in mathematica syntax : Function of a function
hi, What I want to do is to : Plot Reflectivity: Refelectivity is an expression ( or a function ) depending on nfilm which in turn depends on epsmodel( which in itself is a function of 3 parameters and a variable ) therefore : epsmodel = f(a,b,c,d,x) (* result is a comlpex number *) nfilm = sqrt[epsmodel] reflectivity = ((nfilm - 1) / (nfilm +1))^2 I just want to plot reflectivity and see the variation in it when (a,b,c,x) varies ( using the Manipulate[] tool ) Please let me know how to do this in term of these functions ? the exact formalism for which I got the error : ...

Re: EUREKA Re: Types in Mathematica, a practical example
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