I draw a graph in Latex but I'm having a problem in placing the caption of the graph since I want it be exactly below my graph at the left side of the page but it's always in the center regardless to whatever I do in order to bringin it to the left side , I'm using picture enviroment . 
I also looked at the similar problems but the solution did not work . 
this is the code which I'm using . which changes should I make in order to solve this problem?
‎here I put 2 codes one of them is when i'm not using English and all the commands will work but the second one is when I'm using Farsi language where this problem remains :

```
\documentclass[a4]‎{‎book‎}‎‎ 
‎‎
‎\usepackage{color}‎
\usepackage{graphicx}‎
\usepackage{pict2e} ‎‎‎‎
‎\textwidth =12cm‎ 
‎\textheight =19cm‎
‎\usepackage{amsmath,amssymb}‎‎ 
‎\usepackage{pict2e}‎
‎‎ ‎ ‎
‎‎
‎\begin{document}‎‎
‎‎‎‎‎‎
‎\begin{figure}‎[htp!]‎
‎\setlength{‎\‎unitlength}{0.‎1c‎m}‎
\linethickness{0.3mm}‎‎ ‎‎‎‎‎
‎\begin{picture}(‎0‎‎‎,‎2‎0‎)‎
‎\put(‎0‎‎,0){\vector(1,0){40}}‎‎
\put(42,0){‎$‎x$}‎
\put(‎0,‎‎0){\vector(0,1){‎3‎0}}‎
\put(0,‎3‎2){‎$‎y$}‎‎
‎\put(0,0){\color{red}\vector(2,1){30}‎} ‎‎
\put(30‎‎,‎1‎6‎){‎$‎(‎‎x,y)$} ‎‎
\put(‎29‎,-‎4‎){‎$‎x‎$‎}‎
\put(-‎4‎,16){‎$‎y$}‎
‎\put(‎9‎‎‎,‎1‎‎‎){‎$‎\theta‎$}‎
\put(‎1‎4‎,‎10‎‎){‎$‎r‎$‎}
\multiput(0,‎15‎‎)‎(‎0.‎8‎‎‎,0‎)‎{‎38‎‎‎‎‎‎}‎{\line(1,0){‎0.‎3}}‎‎ 
\multiput(‎29.5‎‎‎,0‎‎‎)‎(‎0‎‎‎‎,0‎.8‎‎)‎{‎20‎‎‎‎‎‎‎‎}‎{\line(‎0‎,‎1‎){‎0.‎3}}‎‎‎‎‎
\end{picture}‎‎‎‎‎ 
‎\caption{ I‎‎‎‎‎‎‎‎ ‎want ‎name ‎below‎ ‎gragh‎  }‎
‎\end{figure}‎ 
\end{document}‎

```

the Second one : 
‎

```
\documentclass[a4]‎{‎book‎}‎‎ 
‎
\usepackage{caption}‎‎
‎\usepackage{color}‎
\usepackage{graphicx}‎
\usepackage{pict2e} ‎‎‎‎
‎\textwidth =12cm‎ 
‎\textheight =19cm‎
‎\usepackage{amsmath,amssymb}‎‎ 
‎\usepackage{pict2e} ‎‎
‎\usepackage{xepersian}‎
‎\settextfont[Scale=1]{XB Zar}‎
‎\setdigitfont[Scale=1]{XB Zar}‎‎ 
\begin{document}‎
‎\begin{figure}‎[‎!‎hb‎‎]‎‎‎
‎\setlength{‎\‎unitlength}{0.‎1c‎m}‎
\linethickness{0.3mm}‎‎ ‎‎
\begin{LTR}‎
‎\begin{picture}(‎0‎‎‎,‎2‎0‎)‎
‎\put(‎0‎‎,0){\vector(1,0){40}}‎‎
\put(42,0){‎$‎x$}‎
\put(‎0,‎‎0){\vector(0,1){‎3‎0}}‎
\put(0,‎3‎2){‎$‎y$}‎‎
‎\put(0,0){\color{red}\vector(2,1){30}‎} ‎‎
\put(30‎‎,‎1‎6‎){‎$‎(‎‎x,y)$} ‎‎
\put(‎29‎,-‎4‎){‎$‎x‎$‎}‎
\put(-‎4‎,16){‎$‎y$}‎
‎\put(‎9‎‎‎,‎1‎‎‎){‎$‎\theta‎$}‎
\put(‎1‎4‎,‎10‎‎){‎$‎r‎$‎}
\multiput(0,‎15‎‎)‎(‎0.‎8‎‎‎,0‎)‎{‎38‎‎‎‎‎‎}‎{\line(1,0){‎0.‎3}}‎‎ 
\multiput(‎29.5‎‎‎,0‎‎‎)‎(‎0‎‎‎‎,0‎.8‎‎)‎{‎20‎‎‎‎‎‎‎‎}‎{\line(‎0‎,‎1‎){‎0.‎3}}‎‎‎‎‎
\end{picture}‎‎ ‎‎‎
\end{LTR}‎
\captionsetup{singlelinecheck=false}‎‎
‎\caption ‎‎{‎نمایشِ قطبیِ یک نقطه‎}‎ 
‎\end{figure}‎‎
‎\end{document}‎‎

```