diff --git a/doc/src/Eqs/angle_fourier_simple.jpg b/doc/src/Eqs/angle_fourier_simple.jpg
deleted file mode 100644
index 6c9297b970..0000000000
Binary files a/doc/src/Eqs/angle_fourier_simple.jpg and /dev/null differ
diff --git a/doc/src/Eqs/angle_fourier_simple.tex b/doc/src/Eqs/angle_fourier_simple.tex
deleted file mode 100644
index 3228315a13..0000000000
--- a/doc/src/Eqs/angle_fourier_simple.tex
+++ /dev/null
@@ -1,9 +0,0 @@
-\documentclass[12pt]{article}
-
-\begin{document}
-
-$$
-   E = K [ 1.0 + c \cos ( n \theta) ] 
-$$
-
-\end{document}
diff --git a/doc/src/angle_fourier_simple.rst b/doc/src/angle_fourier_simple.rst
index cea83b2fdf..5ad8b386d0 100644
--- a/doc/src/angle_fourier_simple.rst
+++ b/doc/src/angle_fourier_simple.rst
@@ -1,41 +1,45 @@
-.. index:: angle\_style fourier/simple
+.. index:: angle_style fourier/simple
 
-angle\_style fourier/simple command
-===================================
+angle_style fourier/simple command
+==================================
 
-angle\_style fourier/simple/omp command
-=======================================
+angle_style fourier/simple/omp command
+======================================
 
 Syntax
 """"""
 
 
-.. parsed-literal::
+.. code-block:: LAMMPS
 
    angle_style fourier/simple
 
 Examples
 """"""""
 
-angle\_style fourier/simple
-angle\_coeff 100.0 -1.0 1.0
+.. code-block:: LAMMPS
+
+   angle_style fourier/simple
+   angle_coeff 100.0 -1.0 1.0
 
 Description
 """""""""""
 
 The *fourier/simple* angle style uses the potential
 
-.. image:: Eqs/angle_fourier_simple.jpg
-   :align: center
+.. math::
+
+   E = K [ 1.0 + c \cos ( n \theta) ]
+
 
 The following coefficients must be defined for each angle type via the
 :doc:`angle\_coeff <angle_coeff>` command as in the example above, or in
 the data file or restart files read by the :doc:`read\_data <read_data>`
 or :doc:`read\_restart <read_restart>` commands:
 
-* K (energy)
-* c (real)
-* n (real)
+* :math:`K` (energy)
+* :math:`c` (real)
+* :math:`n` (real)
 
 
 ----------
@@ -77,8 +81,3 @@ Related commands
 :doc:`angle\_coeff <angle_coeff>`
 
 **Default:** none
-
-
-.. _lws: http://lammps.sandia.gov
-.. _ld: Manual.html
-.. _lc: Commands_all.html
diff --git a/doc/txt/angle_fourier_simple.txt b/doc/txt/angle_fourier_simple.txt
deleted file mode 100644
index ae5d308353..0000000000
--- a/doc/txt/angle_fourier_simple.txt
+++ /dev/null
@@ -1,70 +0,0 @@
-"LAMMPS WWW Site"_lws - "LAMMPS Documentation"_ld - "LAMMPS Commands"_lc :c
-
-:link(lws,http://lammps.sandia.gov)
-:link(ld,Manual.html)
-:link(lc,Commands_all.html)
-
-:line
-
-angle_style fourier/simple command :h3
-angle_style fourier/simple/omp command :h3
-
-[Syntax:]
-
-angle_style fourier/simple :pre
-
-[Examples:]
-
-angle_style fourier/simple
-angle_coeff 100.0 -1.0 1.0
-
-[Description:]
-
-The {fourier/simple} angle style uses the potential
-
-:c,image(Eqs/angle_fourier_simple.jpg)
-
-The following coefficients must be defined for each angle type via the
-"angle_coeff"_angle_coeff.html command as in the example above, or in
-the data file or restart files read by the "read_data"_read_data.html
-or "read_restart"_read_restart.html commands:
-
-K (energy)
-c (real)
-n (real) :ul
-
-:line
-
-Styles with a {gpu}, {intel}, {kk}, {omp}, or {opt} suffix are
-functionally the same as the corresponding style without the suffix.
-They have been optimized to run faster, depending on your available
-hardware, as discussed on the "Speed packages"_Speed_packages.html doc
-page.  The accelerated styles take the same arguments and should
-produce the same results, except for round-off and precision issues.
-
-These accelerated styles are part of the GPU, USER-INTEL, KOKKOS,
-USER-OMP and OPT packages, respectively.  They are only enabled if
-LAMMPS was built with those packages.  See the "Build
-package"_Build_package.html doc page for more info.
-
-You can specify the accelerated styles explicitly in your input script
-by including their suffix, or you can use the "-suffix command-line
-switch"_Run_options.html when you invoke LAMMPS, or you can use the
-"suffix"_suffix.html command in your input script.
-
-See the "Speed packages"_Speed_packages.html doc page for more
-instructions on how to use the accelerated styles effectively.
-
-:line
-
-[Restrictions:]
-
-This angle style can only be used if LAMMPS was built with the
-USER_MISC package.  See the "Build package"_Build_package.html doc
-page for more info.
-
-[Related commands:]
-
-"angle_coeff"_angle_coeff.html
-
-[Default:] none