add fediverse; add calculus source files; fix calculus stuff

2 files changed, 41 insertions, 2 deletions

diff --git a/website/mathematics/calculus/source/derivative.ms b/website/mathematics/calculus/source/derivative.ms
index 6675046..9e4196f 100644
--- a/website/mathematics/calculus/source/derivative.ms
+++ b/website/mathematics/calculus/source/derivative.ms
@@ -205,10 +205,10 @@ d sub initial = f(t sub {initial})
 d sub final = f(t sub {final})
 .EN
 .EQ
-\[*D] = f(t sub initial + \[*D]t) - d sub initial
+\[*D]t = f(t sub initial + \[*D]t) - d sub initial
 .EN
 .EQ
-\[*D] = f(t sub initial + \[*D]t) - f(t sub {initial})
+\[*D]t = f(t sub initial + \[*D]t) - f(t sub {initial})
 .EN
 .EQ
 f'(t) = {f(t sub initial + \[*D]t) - f(t sub {initial})} over \[*D]t
diff --git a/website/mathematics/calculus/source/index.html b/website/mathematics/calculus/source/index.html
new file mode 100644
index 0000000..52aec9e
--- /dev/null
+++ b/website/mathematics/calculus/source/index.html
@@ -0,0 +1,39 @@
+$$START TITLE
+Calculus
+$$END TITLE
+
+$$START CONTENT
+<h1>Calculus</h1>
+<p>
+Calculus is the age-old study of infinetesimal rates of change.
+I write articles here from the perspective of hyperreal numbers
+instead of using limits because they were the original intuitive
+way that calculus was invented (and how I originally reinvented
+the derivative).
+</p>
+
+<p>
+	You can also <a href="./source">browse the groff source files</a>,
+	as well as use, modify, and distribute them to your liking.
+</p>
+
+<h2>Elementary Calculus</h2>
+<ul>
+	<li><a href="./derivative.pdf">Derivative</a> -- a fundamental operation regarding calculus.</li>
+	<li><a href="./derivative_identities.pdf">Derivative Identities</a> -- Deriving identities related to derivatives of simple functions.</li>
+	<li><a href="./derivative_rules.pdf">Derivative Rules</a> -- Deriving common derivative rules.</li>
+</ul>
+
+<h2>Multivariable</h2>
+<ul>
+	<li><a href="./partial_derivative.pdf">Partial Derivative</a> -- a fundamental operation regarding mulitvariable calculus.</li>
+</ul>
+
+<h2>Source</h2>
+<p>
+	These are the groff source files I compile my PDF from. You're free to download, modify, and distribute them freely.
+</p>
+<ul>
+	<li><a href="./source/"></a></li>
+</ul>
+$$END CONTENT