# Unicode characters in math mode in pdfLaTeX

I can't write Unicode characters in math mode. All current answers for this topic for other typsetting systems, not for pdfLaTeX.

I want to use Unicode in my formula. Even I used \usepackage[utf8]{inputenc}, my code gives error:

\documentclass[11pt,a4paper,oneside]{article}
\usepackage{amsmath}
\usepackage{amssymb}
\usepackage{graphicx}
\usepackage{tikz}
\usepackage{caption}
\usepackage{color}
\usepackage{pgfplots}
\usepackage[utf8]{inputenc}

\begin{document}
Çıkış sıcaklığı
$$T_{çıkış}$$
\end{document}

• use T_{\text{çıkış}} – David Carlisle Jun 2 '18 at 16:57

Use the correct syntax. Anyway, it is a word you want to have subscripted, not the succession of $5$ variables. This works:

\documentclass[11pt, a4paper, oneside]{article}
\usepackage[utf8]{inputenc}
\usepackage[T1]{fontenc}
\usepackage{amsmath}
\usepackage{amssymb}
\usepackage{graphicx}
\usepackage{tikz}
\usepackage{caption}
\usepackage{color}
\usepackage{pgfplots}
$T_{\text{çıkış}}$

Comment aside: use the LaTeX syntax $...$ for displayed equations, not the plain TeX $$...$$, which yields bad spacing. Also, you should load hyperref as the last package(very few exceptions).