patch 7.4.1285
Problem:    Cannot measure elapsed time.
Solution:   Add reltimefloat().
diff --git a/src/eval.c b/src/eval.c
index c2d18aa..787f0f0 100644
--- a/src/eval.c
+++ b/src/eval.c
@@ -690,6 +690,9 @@
 static void f_range(typval_T *argvars, typval_T *rettv);
 static void f_readfile(typval_T *argvars, typval_T *rettv);
 static void f_reltime(typval_T *argvars, typval_T *rettv);
+#ifdef FEAT_FLOAT
+static void f_reltimefloat(typval_T *argvars, typval_T *rettv);
+#endif
 static void f_reltimestr(typval_T *argvars, typval_T *rettv);
 static void f_remote_expr(typval_T *argvars, typval_T *rettv);
 static void f_remote_foreground(typval_T *argvars, typval_T *rettv);
@@ -8270,6 +8273,7 @@
     {"range",		1, 3, f_range},
     {"readfile",	1, 3, f_readfile},
     {"reltime",		0, 2, f_reltime},
+    {"reltimefloat",	1, 1, f_reltimefloat},
     {"reltimestr",	1, 1, f_reltimestr},
     {"remote_expr",	2, 3, f_remote_expr},
     {"remote_foreground", 1, 1, f_remote_foreground},
@@ -16010,6 +16014,26 @@
 #endif
 }
 
+#ifdef FEAT_FLOAT
+/*
+ * "reltimefloat()" function
+ */
+    static void
+f_reltimefloat(typval_T *argvars UNUSED, typval_T *rettv)
+{
+# ifdef FEAT_RELTIME
+    proftime_T	tm;
+# endif
+
+    rettv->v_type = VAR_FLOAT;
+    rettv->vval.v_float = 0;
+# ifdef FEAT_RELTIME
+    if (list2proftime(&argvars[0], &tm) == OK)
+	rettv->vval.v_float = profile_float(&tm);
+# endif
+}
+#endif
+
 /*
  * "reltimestr()" function
  */