[Tex/LaTex] Latex: includegraphics – width and height

Question

The code below is executing properly:

\begin{figure}
\includegraphics{name1}
\caption{Figure 1}\label{name1}
\end{figure}

However when I add width and height:

\begin{figure}
\includegraphics[width=15cm,height=6cm]{name1}
\caption{Figure 1}\label{name1}
\end{figure}

I get this error:

! Missing number, treated as zero.<to be read again>

How do I solve this problem?

Answer 1

The optional argument with key value options are added by package graphicx, note the x at the end. Package graphics has a different syntax and meaning of the optional arguments, from the documentation of packages graphics and graphicx, grfguide:

graphics: \includegraphics[⟨llx,lly⟩][⟨urx,ury⟩]{⟨file⟩}
graphicx: \includegraphics[⟨key val list⟩]{⟨file⟩}

Solution:

\usepackage{graphicx}
...
\includegraphics[width=15cm, height=6cm]{name1}

This might distort the image, if the specifications do not hit the aspect ratio of the image. Option keepaspectratio scales the image down if necessary to fit the available space but without distorting the image:

\includegraphics[
  width=15cm,
  height=6cm,
  keepaspectratio,
]{name1}