# PSTricks: problem with y-coordinate

I have a problem with pstricks. I am not able to control the cartesian coordinate for the y-axis. I don't understand why. For example, I am drawing a line going from (x=1,y=4) to (x=6,y=4). I can control the x-coordinate, but not the y. Anyone can explain me where I am wrong?

Here is my code:

\documentclass[12pt]{article}

\usepackage{pstricks}
\usepackage{pst-node}
\usepackage{pst-tree}
\usepackage{pst-plot}
%\usepackage{pst-math}
\begin{document}

\psgrid
\psset{xunit=1cm,yunit=1cm, fillstyle=solid}

\psline[linewidth=.05cm,arrowsize=0.25]{->}(1,4)(6,4)

\end{document}


And here what I get:

That is the correct behaviour. You didn't reserve any space for the image, the reason why all macros place its contents into a box of zero width and height. You have an empty line between \psset and \psline. For TeX it is the same as \par, which starts a new line and your current reference point (coordinate system) is moved down. Compare it with:

\documentclass[12pt]{article}
\usepackage{pstricks}
\begin{document}

\psgrid
\psset{xunit=1cm,yunit=1cm, fillstyle=solid}%
%
\psline[linewidth=.05cm,arrowsize=0.25]{->}(1,4)(6,4)

\end{document}


However, you are looking for something like

\documentclass[12pt]{article}
\usepackage{pstricks}

\begin{document}

\begin{pspicture}[showgrid](7,5)
\psset{xunit=1cm,yunit=1cm, fillstyle=solid}%

\psline[linewidth=.05cm,arrowsize=0.25]{->}(1,4)(6,4)
\end{pspicture}
\end{document}


The environment pspicture reserves a box of width 7 and height 5. Empty lines are now not valid.