wolfram mathematica - Custom Notation question -

-

i need extract restrict value lists sublists, ie if vals gives values of vars={x1,x2,x3,x4}, , need values of svars={x2,x4} restrict[list,vars,svars]where

restrict[vars_, svars_, vals_] :=   extract[vals, flatten[position[vars, #] & /@ svars, 1]]

i'd improve code readability, perhaps defining following custom notation restrict[vars,svars,vals]

http://yaroslavvb.com/upload/custom-notation.png

my questions are

  1. what way implement this?
  2. is idea altogether?

good notations can useful - i'm not sure particular 1 needed...

that said, notation package makes pretty easy. there many hidden boxes when use notation palette, i'll use screenshot: alt text

you can see underlying notationmake* downvalues construct using action -> printnotationrules option. in[4] in screenshot generates

notationmakeexpression[   subscriptbox[vals_, rowbox[{vars_, "|", svars_}]], standardform] :=   makeexpression[   rowbox[{"restrict", "[", rowbox[{vars, ",", svars, ",", vals}],      "]"}], standardform]  notationmakeboxes[subscript[vals_, vars_ | svars_], standardform] :=   subscriptbox[makeboxes[vals, standardform],    rowbox[{parenthesize[vars, standardform, alternatives], "|",      parenthesize[svars, standardform, alternatives]}]]

Comments

Post a Comment

Popular posts from this blog

c++ - How to modify context menu of internet explorer using IDocHostUIHandler::ShowContextMenu? -

-
i trying implement custom menu internet explorer 7.0. have use idochostuihandler::showcontextmenu only. till able implement basic context menu 2 options. problem disabled default. sample code same is: hresult cwebeventhandler::showcontextmenu(dword dwid,point *ppt, iunknown *pcmdtarget, idispatch *pdispobject) { if (false) // put guard code here. of not consider return s_false; // show standard context menus. else { iolewindow* pwnd = null; hresult hr = pcmdtarget->queryinterface(iid_iolewindow, (void**) &pwnd); if (succeeded(hr)) { hwnd hwnd; if (succeeded(pwnd->getwindow(&hwnd))) { hmenu menu = ::createpopupmenu(); ::appendmenu(menu, mf_string, id_hello, l"&hello" ); // id_hello & id_world 2 menu resource items ::appendmenu(menu, mf_string, id_world, l"&world" ); ...
Read more

android - Spacing between the stars of a rating bar? -

-
ho can set spacing beween stars? thats ratingbar: ratingbar = (ratingbar) inflater.inflate(r.layout.ratingbar, null); ratingbar.setlayoutparams(new layoutparams(layoutparams.wrap_content, layoutparams.wrap_content)); the layout: <?xml version="1.0" encoding="utf-8"?> <ratingbar xmlns:android="http://schemas.android.com/apk/res/android" style="@style/mystyle" android:layout_alignparentright="true" android:layout_height="19dp" android:layout_width="wrap_content" android:numstars="5"> </ratingbar> the style: <style name="mystyle" parent="@android:style/widget.ratingbar"> <item name="android:progressdrawable">@drawable/android_r2_ratingstar_yellow</item> <item name="android:indeterminatedrawable">@drawable/android_r2_ratingstar_grey</item> </style> thanks, cheers you have ...
Read more

c# - Getting "Internal .Net Framework Data Provider error 30" error when column has NULL value -

-
i have simple .net console program uses odbcdatareader fetch rows advantage local server. using system dsn defined via odbc administrator on windows 7. data source uses advantage streamlinesql odbc driver v 10.00.00.03 , following params: database path: table type: advantage available server types: local server (als) the program works fine until encounters row has null value in column. exception: system.invalidoperationexception caught message=internal .net framework data provider error 30. source=system.data stacktrace: @ system.data.providerbase.dbbuffer.validate(int32 offset, int32 count) @ system.data.providerbase.dbbuffer.ptrtostringuni(int32 offset, int32 length) @ system.data.odbc.odbcdatareader.internalgetstring(int32 i) @ system.data.odbc.odbcdatareader.getvalue(int32 i, typemap typemap) @ system.data.odbc.odbcdatareader.getvalue(int32 i) @ system.data.odbc.odbcdatareader.isdbnull(int32 i) @ odbctest.program....
Read more