Add a few function-level comments.

reuleaux.c

@@ -111,6 +111,8 @@ void plot_lr(const double x0, const double y0, const double width, const double
 }
 
 
+/* reuleaux --- draw a Reuleaux polygon centred on (xc, yc) */
+
 void reuleaux(const double xc, const double yc, const double r, const int n, const bool drawSides)
 {
    /* https://en.wikipedia.org/wiki/Reuleaux_triangle */

star_grid.c

@@ -101,6 +101,8 @@ int main(int argc, char * const argv[])
 }
 
 
+/* draw_star --- draw a single star at (x0, y0) */
+
 void draw_star(const double x0, const double y0, const double gridsz, const double xc, const double yc, const int n)
 {
    int i;

superellipse.c

@@ -180,6 +180,8 @@ void plot_ur(const double xc, const double yc, const double r1, const double r2)
 }
 
 
+/* superellipse --- draw a superellipse at (x0, y0) */
+
 void superellipse(const double x0, const double y0, const double a, const double b, const double theta, const double d)
 {
    const int npts = 72;

ternary_arcs.c

@@ -87,6 +87,8 @@ int main(int argc, char * const argv[])
 }
 
 
+/* draw_arcs --- draw arcs or lines at (x, y) */
+
 void draw_arcs(const double x, const double y, const double r, const char str[])
 {
    moveto(x, y + r);