--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,17 @@
+2012-02-29  Bruno Haible  <bruno@clisp.org>
+
+	math code: Add comments.
+	* lib/acosl.c: Add comment about related glibc source files.
+	* lib/asinl.c: Likewise.
+	* lib/atanl.c: Likewise.
+	* lib/expl.c: Likewise.
+	* lib/logl.c: Likewise.
+	* lib/sincosl.c: Likewise.
+	* lib/sinl.c: Likewise.
+	* lib/tanl.c: Likewise.
+	* lib/trigl.c: Likewise.
+	* lib/cosl.c: Likewise. Fix comments.
+
 2012-02-28  Bruno Haible  <bruno@clisp.org>
 
 	math: Ensure HUGE_VAL, HUGE_VALF, HUGE_VALL are defined.

--- a/lib/acosl.c
+++ b/lib/acosl.c
@@ -24,6 +24,9 @@
 
 #else
 
+/* Code based on glibc/sysdeps/ieee754/ldbl-128/e_asinl.c
+   and           glibc/sysdeps/ieee754/ldbl-128/e_acosl.c.  */
+
 /*
   Long double expansions contributed by
   Stephen L. Moshier <moshier@na-net.ornl.gov>

--- a/lib/asinl.c
+++ b/lib/asinl.c
@@ -24,6 +24,8 @@
 
 #else
 
+/* Code based on glibc/sysdeps/ieee754/ldbl-128/e_asinl.c.  */
+
 /*
   Long double expansions contributed by
   Stephen L. Moshier <moshier@na-net.ornl.gov>

--- a/lib/atanl.c
+++ b/lib/atanl.c
@@ -28,6 +28,8 @@
 
 #else
 
+/* Code based on glibc/sysdeps/ieee754/ldbl-128/s_atanl.c.  */
+
 /*                                                      s_atanl.c
  *
  *      Inverse circular tangent for 128-bit long double precision

--- a/lib/cosl.c
+++ b/lib/cosl.c
@@ -28,12 +28,14 @@
 
 #else
 
-/* sinl(x)
- * Return sine function of x.
+/* Code based on glibc/sysdeps/ieee754/ldbl-128/s_cosl.c.  */
+
+/* cosl(x)
+ * Return cosine function of x.
  *
  * kernel function:
  *      __kernel_sinl           ... sine function on [-pi/4,pi/4]
- *      __kernel_cosl           ... cose function on [-pi/4,pi/4]
+ *      __kernel_cosl           ... cosine function on [-pi/4,pi/4]
  *      __ieee754_rem_pio2l     ... argument reduction routine
  *
  * Method.

--- a/lib/expl.c
+++ b/lib/expl.c
@@ -33,6 +33,8 @@
 
 #else
 
+/* Code based on glibc/sysdeps/ieee754/ldbl-128/e_expl.c.  */
+
 # include <float.h>
 
 static const long double C[] = {

--- a/lib/logl.c
+++ b/lib/logl.c
@@ -28,6 +28,8 @@
 
 #else
 
+/* Code based on glibc/sysdeps/ieee754/ldbl-128/e_logl.c.  */
+
 /*                                                      logll.c
  *
  * Natural logarithm for 128-bit long double precision.

--- a/lib/sincosl.c
+++ b/lib/sincosl.c
@@ -24,6 +24,10 @@
 #include <float.h>
 #include <math.h>
 
+/* Code based on glibc/sysdeps/ieee754/ldbl-128/k_sincosl.c
+   or            glibc/sysdeps/ieee754/ldbl-128/k_{sin,cos}l.c
+   and           glibc/sysdeps/ieee754/ldbl-128/t_sincosl.c.  */
+
 static const long double sin_c[] = {
 #define ONE sin_c[0]
   1.00000000000000000000000000000000000E+00L,   /* 3fff0000000000000000000000000000 */

--- a/lib/sinl.c
+++ b/lib/sinl.c
@@ -28,12 +28,14 @@
 
 #else
 
+/* Code based on glibc/sysdeps/ieee754/ldbl-128/s_sinl.c.  */
+
 /* sinl(x)
  * Return sine function of x.
  *
  * kernel function:
  *      __kernel_sinl           ... sine function on [-pi/4,pi/4]
- *      __kernel_cosl           ... cose function on [-pi/4,pi/4]
+ *      __kernel_cosl           ... cosine function on [-pi/4,pi/4]
  *      __ieee754_rem_pio2l     ... argument reduction routine
  *
  * Method.

--- a/lib/tanl.c
+++ b/lib/tanl.c
@@ -29,6 +29,9 @@
 
 #else
 
+/* Code based on glibc/sysdeps/ieee754/ldbl-128/s_tanl.c
+   and           glibc/sysdeps/ieee754/ldbl-128/k_tanl.c.  */
+
 /* tanl(x)
  * Return tangent function of x.
  *

--- a/lib/trigl.c
+++ b/lib/trigl.c
@@ -24,6 +24,9 @@
 #include <float.h>
 #include <math.h>
 
+/* Code based on glibc/sysdeps/ieee754/ldbl-128/e_rem_pio2l.c
+   and           glibc/sysdeps/ieee754/dbl-64/k_rem_pio2.c.  */
+
 /* Table of constants for 2/pi, 5628 hexadecimal digits of 2/pi */
 static const int two_over_pi[] = {
   0xa2f983, 0x6e4e44, 0x1529fc, 0x2757d1, 0xf534dd, 0xc0db62,