Drop LaTeX dependency via usage of sphinx.ext.imgmath in Vector Math tutorial

It's the only tutorial where we used the extension for *3* formulas which anyway
ended up as fairly low res static images generated by sphinx.ext.imgmath, so
requiring ~1 GB of LaTeX setup for it is overkill.

The replacement pictures are the ones generated by sphinx.ext.imgmath, we could
replace them by higher resolution ones.

Makefile

@@ -13,10 +13,6 @@ ifeq ($(shell which $(SPHINXBUILD) >/dev/null 2>&1; echo $$?), 1)
 $(error The '$(SPHINXBUILD)' command was not found. Make sure you have Sphinx installed, then set the SPHINXBUILD make variable to point to the full path of the '$(SPHINXBUILD)' executable. Alternatively you can add the directory with the executable to your PATH. If you don't have Sphinx installed, grab it from http://sphinx-doc.org/)
 endif
 
-# check for latex dependencies
-E := $(foreach exec, $(LATEXDEPS),\
-	$(if $(shell which $(exec)), some string,$(warning The $(exec) command was not found: math formulas will not be built. LaTeX is required for math formula support. If you don't have LaTeX installed, grab it from https://www.latex-project.org/get/)))
-
 # Internal variables.
 PAPEROPT_a4     = -D latex_paper_size=a4
 PAPEROPT_letter = -D latex_paper_size=letter

conf.py

@@ -14,7 +14,6 @@ needs_sphinx = "1.3"
 sys.path.append(os.path.abspath("_extensions"))
 extensions = [
     "sphinx_tabs.tabs",
-    "sphinx.ext.imgmath",
 ]
 
 # Warning when the Sphinx Tabs extension is used with unknown

tutorials/math/vector_math.rst

@@ -257,15 +257,11 @@ direction, a scalar value has only magnitude.
 
 The formula for dot product takes two common forms:
 
-.. math::
-
-    A \cdot B = \left \| A \right \|\left \| B \right \|\cos \Theta
+.. image:: img/vector_dot1.png
 
 and
 
-.. math::
-
-    A \cdot B = A_{x}B_{x} + A_{y}B_{y}
+.. image:: img/vector_dot2.png
 
 However, in most cases it is easiest to use the built-in method. Note that
 the order of the two vectors does not matter:
@@ -332,11 +328,9 @@ However, the result of the cross product is a vector with a direction
 that is perpendicular to both. Its magnitude depends on their relative angle.
 If two vectors are parallel, the result of their cross product will be a null vector.
 
-.. math::
+.. image:: img/vector_cross1.png
 
-    \left \|a \times b  \right \| = \left \| a \right \|\left \| b \right \|\ |\sin(a,b)|
-
-.. image:: img/tutovec16.png
+.. image:: img/vector_cross2.png
 
 The cross product is calculated like this: