minor changes

Author: wldfngrs

libc/src/math/generic/acosf16.cpp

@@ -24,7 +24,7 @@ namespace LIBC_NAMESPACE_DECL {
 // Generated by Sollya using the following command:
 // > round(pi/2, SG, RN);
 // > round(pi, SG, RN);
-static constexpr float PI_2 = 0x1.921fb6p0f;
+static constexpr float PI_OVER_2 = 0x1.921fb6p0f;
 static constexpr float PI = 0x1.921fb6p1f;
 
 static constexpr size_t N_EXCEPTS = 2;
@@ -98,9 +98,9 @@ LLVM_LIBC_FUNCTION(float16, acosf16, (float16 x)) {
   // 2:  From complimentary angle identity:
   //       x = sin(y) = cos(pi/2 - y)
   // 3:  Let z = pi/2 - y, such that x = cos(z)
-  // 4:  From double angle formula; cos(2A) = 1 - sin^2(A):
+  // 4:  From double angle formula; cos(2A) = 1 - 2 * sin^2(A):
   //       z = 2A, z/2 = A
-  //       cos(z) = 1 - 2 * sin*2(z/2)
+  //       cos(z) = 1 - 2 * sin^2(z/2)
   // 5:  Make sin(z/2) subject of the formula:
   //       sin(z/2) = sqrt((1 - cos(z))/2)
   // 6:  Recall [3]; x = cos(z). Therefore: