2

I am trying to reproduce this excellent picture enter image description here

but I ended quite soon with errors:

C:\Program Files (x86)\MiKTeX 2.9\tex\latex\pgfplots\pgfplots.sty:48: Package pgfkeys Error: I do not know the key '/tikz/$w(x)', to which you passed '(b - x)^{\alpha }(x - a)^{\beta }$', and I am going to ignore it. Perhaps you misspelled it. [\end{forest}] C:\Program Files (x86)\MiKTeX 2.9\tex\latex\pgfplots\pgfplots.sty:48: Missing $ inserted. [\end{forest}]

\documentclass[]{standalone}
\usepackage[utf8]{inputenc}
\usepackage[czech]{babel}
\usepackage{amsmath}
\usepackage{amsfonts}
\usepackage{amssymb}
\usepackage{graphicx}
\usepackage{float}
\usepackage{forest}
\usepackage{tikz}
\usepackage{pgfplots}

\forestset{qtree/.style={for tree={parent anchor=south, 
           child anchor=north,align=center,inner sep=0pt}}}

\begin{document}


\begin{forest}baseline, qtree
 [Obecné Jakobiho polynomy $P_n^{(\alpha,\beta)}$ \\ $X = (b - x)(x - a)$, $w(x) = (b - x)^{\alpha}(x - a)^{\beta}$
 [DP]
 [V’
 [V[sent]]
 [DP[Mary]]
 [DP[D[a]][NP[letter]]]
 ]
 ]
\end{forest}



\end{document}

What is wrong? Is it possible to make left and right aligned math as in the original tree?

  • 1
    Everything after the comma following a node label is interpreted as TikZ options passed to forest. Enclose the second line of the math in {} to solve that. That's the source of the error. But it's very unclear to me why you would format the image you show with a tree. I would use a matrix structure instead. – Alan Munn Mar 14 '18 at 15:24
  • Ok, it worked. I will put the rest of the code for the future public use :) – Jan Filip Mar 14 '18 at 15:57
  • It would be more usual to ask @AlanMunn to post an answer, rather than taking the credit by posting his solution as your own. [But I also agree that a tree structure seems a rather awkward choice in this case.] – cfr Mar 15 '18 at 4:16
  • Ok, I am going to delete question – Jan Filip Mar 15 '18 at 7:18
2

mostly off-topic (as supplement to op answer) ...

  • for edge labels is sensible define node style with use tikzset out of forest environment. with this code will become slightly shorter
  • code of the tree is easier to understand and maintain if it has the shape of a tree

\documentclass[margin=3mm]{standalone}
\usepackage[utf8]{inputenc}
\usepackage[czech]{babel}
\usepackage{forest}

\tikzset{EL/.style={%Edge Labels
                    midway,
                    #1,% <--- position: left or right
                    inner xsep=6pt,
                    font=\small,
                    align=center,
                        }
        }
\forestset{qtree/.style={
    for tree={align=center,
              inner sep=0pt,
              %
              edge = {draw, semithick, -stealth},
              l sep=4em, s sep=3em
              }}
          }
\begin{document}
    \begin{forest}qtree
[obecné Jakobiho polynomy $P_n^{(\alpha,\beta)}$ \\
 {$X = (b - x)(x - a)$,\qquad $w(x) = (b - x)^{\alpha}(x - a)^{\beta}$} \\
  {$\alpha > -1$, $\beta> 1$}
    [zjednodušené Jakobiho polynomy $P_n^{(\alpha,\beta)}$ \\
     {$X = 1 - x^2$, $w(x) = (1 - x)^{\alpha}(1 + x)^{\beta}$},
     edge label={node[EL=right] {omezení na $-1 \leq x \leq +1$\\
                                $a = -1$, $b = +1$}}
        [ultrasférické polynomy (Gegenbauerovy) $F_n^{(\lambda)}$ \\
         {$X = 1 - x^2$, $w(x) = (1 - x^2)$},
         edge label={node[EL=right] {omezení na $\alpha = \beta = \lambda$}}
            [Legendrovy polynomy $L_n(x)$ \\
             {$X = 1 - x^2$, $w(x) = 1$},
             edge label={node[EL=left] {$\lambda = 0$\quad}}]
            [Čebyševovy polynomy I. druhu $T_n(x)$ \\
             {$X = 1 - x^2$, $w(x) = (1 - x^2)^{-1/2}$},
              edge label={node[EL=right] {$\lambda = -\frac{1}{2}$}}
              [Čebyševovy polynomy II. druhu $U_n(x)$ \\
               {$X = 1 - x^2$, $w(x) = (1 - x^2)^{+1/2}$},
               edge label={node[EL=right] {$\lambda = +\frac{1}{3}$}}]
            ]
        ]
    ]
]
    \end{forest}
\end{document}

enter image description here

  • Are you sure that qtree is reserved in TikZ? Can you point to a reference or the code which defines it? At most, I would think this might be defined by tikz-qtree, but even that doesn't define it, as far as I can tell. It is, however, a recipe for confusion if the OP also uses qtree or tikz-qtree, though there is no particular evidence of that. – cfr Mar 15 '18 at 4:14
  • @cfr, since i'm not sure i remove my suspicion and change name back to original used. – Zarko Mar 15 '18 at 5:21
1

Here is the result if someone interested in ortogonal polynomials :)

\documentclass[]{standalone}
\usepackage[utf8]{inputenc}
\usepackage[czech]{babel}
\usepackage{amsmath}
\usepackage{amsfonts}
\usepackage{amssymb}
\usepackage{graphicx}
\usepackage{float}
\usepackage{forest}

\forestset{qtree/.style={for tree={parent anchor=south, 
           child anchor=north,align=center,inner sep=0pt,l sep=4em, s sep=8em}}}

\begin{document}

    \begin{forest}baseline, qtree 
     [obecné Jakobiho polynomy $P_n^{(\alpha,\beta)}$ \\ {$X = (b - x)(x - a)$,\qquad $w(x) = (b - x)^{\alpha}(x - a)^{\beta}$} \\ {$\alpha > -1$, $\beta> 1$}
     [zjednodušené Jakobiho polynomy $P_n^{(\alpha,\beta)}$ \\ {$X = 1 - x^2$, $w(x) = (1 - x)^{\alpha}(1 + x)^{\beta}$}, edge label={node[midway,right, align=left]{omezení na $-1 \leq x \leq +1$\\$a = -1$, $b = +1$}}
     [ultrasférické polynomy (Gegenbauerovy) $F_n^{(\lambda)}$ \\ {$X = 1 - x^2$, $w(x) = (1 - x^2)$}, edge label={node[midway,right, align=left]{omezení na $\alpha = \beta = \lambda$}}
    [Legendrovy polynomy $L_n(x)$ \\ {$X = 1 - x^2$, $w(x) = 1$},edge label={node[midway,left, align=left]{$\lambda = 0$\quad}}] [Čebyševovy polynomy I. druhu $T_n(x)$ \\ {$X = 1 - x^2$, $w(x) = (1 - x^2)^{-1/2}$},edge label={node[midway,right, align=left]{\quad $\lambda = -\frac{1}{2}$}} [Čebyševovy polynomy II. druhu $U_n(x)$ \\ {$X = 1 - x^2$, $w(x) = (1 - x^2)^{+1/2}$},edge label={node[midway,right, align=left]{\quad $\lambda = +\frac{1}{2}$}}]
    ]
    ]
     ]
     ]
    \end{forest}
\end{document}

which yieldsenter image description here

  • it will be nice if you in your answer provide complete document with necessary packages loaded in preamble. – Zarko Mar 14 '18 at 16:17
  • Ok, done. The last thing remains, I can't manage how to use arrows instead of lines. If anyone can easily do it, please share – Jan Filip Mar 14 '18 at 16:43
  • to qtree style add line edge = {draw, semithick, -stealth},. be so kind and format your code, that already in editor we can see tree structure. – Zarko Mar 14 '18 at 16:48

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