How can I draw this figure in TikZ?

Question

Here's my attempts,

\begin{document}
\begin{tikzpicture} 
\draw[very thin, gray!15!black, dashed] (1,0) -- (1,5.5) (5,0) --(5,5.5);
\draw[thick, black!50!gray]  (1,0) rectangle (2,3) (2,0) rectangle (3,4) (3,0) rectangle (4,4.6) (4,0) rectangle (5,5);
 \path  (1,0) node[below]{$a$} (5,0) node[below]{$b$} (3,0) node[below]{ $a+k(\frac{b-a}{n})$}(3,5)  node[font=\normalsize]{$f(x)$}; 
\draw[thick,-latex] (-0.5,0) -- (6,0); 
\draw[thick,-latex] (0,-0.5) -- (0,5.7);
\end{tikzpicture}

The problem now is the curve.

Using TikZ how can I draw this?

Welcome to TeX.SE. This is not a ''Do that for me'' site. Please show us what have tried so far. — rsa-krypto, Jul 18 '20 at 14:20
You might check out the section in the PGF manual on data visualizaton. — John Kormylo, Jul 18 '20 at 14:56
Related : A rough version. Riemann Integral on Tikz with commands — AndréC, Jul 18 '20 at 17:59
Hi and welcome. Please change the title of your question so that it clearly indicates the problem posed, making it easier for search engines to index it. — AndréC, Jul 18 '20 at 18:01
@Amölme Normally you can edit the title and content of your question without asking permission by clicking on the edit button. — AndréC, Jul 19 '20 at 17:57

score 4 · Accepted Answer · answered Jul 18 '20 at 16:43

Here is something you can achieve by choosing a function for your curve. Then, everything is defined with respect to this function declared with the declare function key and can be changed to adapt to the needs of the user.

\documentclass{standalone}
\usepackage{tikz}
    \usetikzlibrary{arrows.meta}
    \usetikzlibrary{calc}
\begin{document}
\begin{tikzpicture}[
    declare function = {localplot(\x) = sqrt(2*\x + 1);}
]

    \draw[-Latex] (-1, 0) -- (5, 0);

    \draw[
        domain  = -0.25:4.25,
        samples = 200
    ] plot ({\x}, {localplot(\x)});

    \foreach \x in {0,0.5,...,3.5} {
        \draw (\x, 0) rectangle ({\x + 0.5}, {localplot(\x)});
    }

    \draw (0, -0.2) -- (0, {localplot(4.25) + 0.1});
    \draw (4, -0.2) -- (4, {localplot(4.25) + 0.1});

    \fill (0, 0) circle (0.05)
        node[below right] {$a$};
    \fill (4, 0) circle (0.05)
        node[below left] {$b$};

    \fill (2, 0) circle (0.05)
        node[below] {$a + k\left(\frac{b - a}{n}\right)$};

\end{tikzpicture}


\end{document}

This code yields:

How can I draw this figure in TikZ?

1 Answers1