Is there a way to search a PDF for non-alphanumeric characters (e.g., the integral sign or greek letters)?

Question

I read a lot of technical papers and textbooks in PDF that use standard mathematical notation, and sometimes I'd like to be able to find where a symbol is in the text. The only reason I think this might even be possible is that I can select them with the select tool just the same as any other text. Right now I'm looking at a formula that includes a constant delta, and it would be nice to be able to search the PDF for instances of delta so I can find what the definition is here. I've tried using ascii codes for some things and putting them into the search bar in FoxitReader, but it doesn't find the symbols. I'm willing to use any PDF reader on Windows or Linux that has this functionality.

Thanks!

EDIT: What I mean when I say I've tried to use the ASCII code is that I've used alt+... to type the character (or used the Character Map) and put them into the search bar. No luck.

Answer 1

You need to use actual symbol. You can get them from character map.

Another option would be to use greek keyboard layout. You could also try using some hotkey program and character map.This way you could set common characters to be on some easily accessible hotkey.

Another option would be to use modifier keys and custom keyboard layout. You could use for example this to make your own keyboard which would have easily accessible letters such as sigma or delta. You could use alt as a modifier key for accessing those characters or shift+alt or something similar.

I have no problems searching non-ascii characters in PDFs in Sumatra, so you could try it if nothing else works.

Depending on which code pages your system uses, you may have some luck with alt codes (looks like there's hack to make it work with Unicode too!). Turn on num lock and press right alt (may work with left too in some cases). Then type a number on keypad and release the alt key. On some codepages (like this one), ALT+235 can make "δ", but I get "в" instead. If ALT codes do work for you, take a look here. Alt codes for often used mathematical symbols can be found there.

Also the document itself needs to be searchable. If mathematical symbols are shown as images instead of text, I really don't know how you'd search for them.