From db35cd5887e81b0470175537d00a66dc8665793b Mon Sep 17 00:00:00 2001
From: Julian Weigt <juw@posteo.de>
Date: Mon, 9 Feb 2026 13:03:04 +0100
Subject: Add readme.

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+For functions f on the discrete circle {0,…,N-1} this program computes their uncentered maximal functions and the ratio of the L<sup>p</sup> norms of the kth derivative of the maximal function and the function.
+
+# Building
+
+If `git` is installed you can fetch the repository using
+
+```
+git clone https://cgit.jnwt.eu/discretemf
+```
+
+The program is written in C and hence requires a C compiler for building. If `make` and `gcc` are installed then running
+
+```
+make
+```
+
+builds three files:
+
+- `charf_approx` does computations using floating point (`double`) numbers, which come with rounding errors.
+- `charf_error` does computations using floating point (`double`) numbers and gives an upper bound for the total rounding error.
+- `charf_exact` does exact computations using fractions. Nominator and denominator are of type `unsigned long long` and bounded in size accordingly.
+
+# Correctness
+
+I am relatively confident that the error bounds are correct for all operations except exponentiation, which is not used for p∈{1,∞}.
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