fixed some reference errors

[rrdtool.git] / doc / rrdtutorial.pod

diff --git a/doc/rrdtutorial.pod b/doc/rrdtutorial.pod
index 04b0d23..e29cd50 100644 (file)
--- a/doc/rrdtutorial.pod
+++ b/doc/rrdtutorial.pod
@@ -56,7 +56,7 @@ element. As we are on a circle there is neither a beginning nor an end, you can
 go on and on and on. After a while, all the available places will be used and
 the process automatically reuses old locations. This way, the dataset
 will not grow in size and therefore requires no maintenance.
-RRDtool works with with Round Robin Databases (RRDs). It stores and retrieves
+RRDtool works with Round Robin Databases (RRDs). It stores and retrieves
 data from them.
 
 =head2 What data can be put into an RRD?
@@ -90,7 +90,7 @@ transferred from and to a network or a computer.  But it can also be
 used to display tidal waves, solar radiation, power consumption,
 number of visitors at an exhibition, noise levels near an airport,
 temperature on your favorite holiday location, temperature in the
-fridge and whatever you imagination can come up with.
+fridge and whatever your imagination can come up with.
 
 You only need a sensor to measure the data and be able to feed the
 numbers into RRDtool. RRDtool then lets you create a database, store
@@ -323,13 +323,18 @@ It should return the following output:
  920808600: 6.6666666667e-03
  920808900: 3.3333333333e-03
  920809200: nan
-
-If it doesn't, something may be wrong.  Perhaps your OS will print
-"NaN" in a different form. "NaN" stands for "Not A Number".  If your OS
-writes "U" or "UNKN" or something similar that's okay.  If something
-else is wrong, it will probably be due to an error you made (assuming
-that my tutorial is correct of course :-). In that case: delete the
-database and try again. 
+ 920809500: nan 
+
+Note that you might get more rows than you expect. The reason for this is
+that you ask for a time range that ends on 920809200. The number that is
+written behind 920809200: in the list above covers the time range from
+920808900 to 920809200, EXCLUDING 920809200. Hence to be on the sure side,
+you receive the entry from 920809200 to 920809500 as well since it INCLUDES
+920809200. You may also see "NaN" instead of "nan" this is OS dependent.
+"NaN" stands for "Not A Number".  If your OS writes "U" or "UNKN" or
+something similar that's okay.  If something else is wrong, it will probably
+be due to an error you made (assuming that my tutorial is correct of course
+:-). In that case: delete the database and try again.
 
 
 The meaning of the above output will become clear below.