How can I select and specify a font which contains the character I have in my file ?
Missing character: There is no ℕ in font cmss10!
I can see them perfectly within emacs, but I am unable to process them with xelatex because of this error
(edit) in emacs ℕ is said to be :
position: 129 of 190 (67%), column: 14
character: ℕ (displayed as ℕ) (codepoint 8469, #o20425, #x2115)
preferred charset: unicode (Unicode (ISO10646))
code point in charset: 0x2115
script: symbol
syntax: w which means: word
category: .:Base, L:Left-to-right (strong)
to input: type "\Bbb{N}" or "\bn" with Agda input method
buffer code: #xE2 #x84 #x95
file code: #xE2 #x84 #x95 (encoded by coding system utf-8-unix)
display: by this font (glyph code)
mac-ct:-*-Arial Unicode MS-bold-normal-normal-*-12-*-*-*-p-0-iso10646-1 (#xD24)

\usepackage{amssymb}and$\mathbb{N}$does it. What's the purpose of comparing the font substitutions Emacs makes with typesetting? – egreg Apr 25 '16 at 08:52unicode-mathpackage, if you want to input your math as unicode characters. – Henri Menke Apr 25 '16 at 09:03