eval: add support for pow() function

It is a more search-friendly alternative to the ^ operator.

doc/eval.texi

@@ -79,6 +79,10 @@ Compute the square root of @var{expr}. This is equivalent to
 
 @item not(expr)
 Return 1.0 if @var{expr} is zero, 0.0 otherwise.
+
+@item pow(x, y)
+Compute the power of @var{x} elevated @var{y}, it is equivalent to
+"(@var{x})^(@var{y})".
 @end table
 
 Note that:

libavutil/avutil.h

@@ -41,7 +41,7 @@
 
 #define LIBAVUTIL_VERSION_MAJOR 51
 #define LIBAVUTIL_VERSION_MINOR  6
-#define LIBAVUTIL_VERSION_MICRO  0
+#define LIBAVUTIL_VERSION_MICRO  1
 
 #define LIBAVUTIL_VERSION_INT   AV_VERSION_INT(LIBAVUTIL_VERSION_MAJOR, \
                                                LIBAVUTIL_VERSION_MINOR, \

libavutil/eval.c

@@ -290,6 +290,7 @@ static int parse_primary(AVExpr **e, Parser *p)
     else if (strmatch(next, "trunc" )) d->type = e_trunc;
     else if (strmatch(next, "sqrt"  )) d->type = e_sqrt;
     else if (strmatch(next, "not"   )) d->type = e_not;
+    else if (strmatch(next, "pow"   )) d->type = e_pow;
     else {
         for (i=0; p->func1_names && p->func1_names[i]; i++) {
             if (strmatch(next, p->func1_names[i])) {
@@ -643,6 +644,10 @@ int main(void)
         "not(1)",
         "not(NAN)",
         "not(0)",
+        "pow(0,1.23)",
+        "pow(PI,1.23)",
+        "PI^1.23",
+        "pow(-1,1.23)",
         NULL
     };