Fix/add some comments.

2 files changed, 3 insertions, 1 deletions

diff --git a/src/phi2.cpp b/src/phi2.cpp
index 7bbb5679..b9b37765 100644
--- a/src/phi2.cpp
+++ b/src/phi2.cpp
@@ -127,7 +127,7 @@ double pj_phi2(projCtx ctx, const double ts0, const double e) {
    * OLD: This routine inverts this relation using the iterative scheme given
    * by Snyder (1987), Eqs. (7-9) - (7-11).
    *
-   * NEW: This routine writes converts t = exp(-psi) to
+   * NEW: This routine converts t = exp(-psi) to
    *
    *   tau' = sinh(psi) = (1/t - t)/2
    *
diff --git a/src/projections/merc.cpp b/src/projections/merc.cpp
index e5da3967..39685478 100644
--- a/src/projections/merc.cpp
+++ b/src/projections/merc.cpp
@@ -13,6 +13,8 @@ PROJ_HEAD(webmerc, "Web Mercator / Pseudo Mercator") "\n\tCyl, Ell\n\t";
 static PJ_XY merc_e_forward (PJ_LP lp, PJ *P) {          /* Ellipsoidal, forward */
     PJ_XY xy = {0.0,0.0};
     xy.x = P->k0 * lp.lam;
+    // Instead of calling tan and sin, call sin and cos which the compiler
+    // optimizes to a single call to sincos.
     double sphi = sin(lp.phi), cphi = cos(lp.phi);
     xy.y = P->k0 * (asinh(sphi/cphi) - P->e * atanh(P->e * sphi));
     return xy;