Re: Symbol ... in part assignment does not have an immediate value
- To: mathgroup at smc.vnet.net
- Subject: [mg22448] Re: Symbol ... in part assignment does not have an immediate value
- From: "Allan Hayes" <hay at haystack.demon.co.uk>
- Date: Wed, 8 Mar 2000 02:21:48 -0500 (EST)
- References: <89qfik$a9t@smc.vnet.net>
- Sender: owner-wri-mathgroup at wolfram.com
Hans, A symbol gets an immediate value from an assigment using = rather than :=. For part assigment to work for a symbol it must have an immediate value, which can, however, have been modified. This is reasonable since part assignment work directly on the stored rule, so the structure must be immediately evident and not rely on further evaluations. d1 = {a, b}; d1[[2]] := 2 + 2; d1[[1]] = 2 + 2; Definition[d1] // InputForm d1 = {4, 2 + 2} But d2 := {a, b}; d2[[1]] = 5; Set::"noval": "Symbol \!\(d2\) in part assignment does not have an immediate \ value." Definition[d2] // InputForm d2 := {a, b} Allan --------------------- Allan Hayes Mathematica Training and Consulting Leicester UK www.haystack.demon.co.uk hay at haystack.demon.co.uk Voice: +44 (0)116 271 4198 Fax: +44 (0)870 164 0565 "Hans Friedrich Steffani" <hans.steffani at e-technik.tu-chemnitz.de> wrote in message news:89qfik$a9t at smc.vnet.net... > > If[ N[nullpos[[i, 2]]/nullpos[[i, 3]]] >= 2.0, > Do[ > nullimpuls[[nullpos[[i, 2]] + > Round[j nullpos[[i, 2]]/nullpos[[i, 3]]] ]] = -1; > {j, 1, Round[nullpos[[i, 2]]/nullpos[[i, 3]] ]}]] > > i is the iterator of an outer loop. > > This code produces: > Set::"noval": "Symbol \!\(nullimpuls\) in part assignment does not > have an immediate value." > > What's that? > > Hans Friedrich Steffani > -- > Hans Friedrich Steffani > Institut fuer Elektrische Maschinen und Antriebe, TU Chemnitz > mailto:hans.steffani at e-technik.tu-chemnitz.de > http://www.tu-chemnitz.de/~hfst/ >