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diff --git a/source/lang/randomseed.rst b/source/lang/randomseed.rst index 3dcf4db..d0a15b7 100644 --- a/source/lang/randomseed.rst +++ b/source/lang/randomseed.rst @@ -1,73 +1,60 @@ -.. _lang-randomseed: +.. highlight:: cpp -randomSeed(seed) -================ +.. _lang-randomseed: -Description ------------ +randomSeed() +============ -randomSeed() initializes the pseudo-random number generator, +``randomSeed()`` initializes the `pseudorandom number generator +<http://en.wikipedia.org/wiki/Pseudorandom_number_generator>`_, causing it to start at an arbitrary point in its random sequence. This sequence, while very long, and random, is always the same. +Library Documentation +--------------------- -If it is important for a sequence of values generated by random() -to differ, on subsequent executions of a sketch, use randomSeed() -to initialize the random number generator with a fairly random -input, such as analogRead() on an unconnected pin. +.. doxygenfunction:: randomSeed +Discussion +---------- +If it is important for a sequence of values generated by +:ref:`random() <lang-random>` to differ, on subsequent executions of a +sketch, use ``randomSeed()`` to initialize the random number generator +with a fairly random input, such as :ref:`analogRead() +<lang-analogread>` on an unconnected pin. -Conversely, it can occasionally be useful to use pseudo-random +Conversely, it can occasionally be useful to use pseudorandom sequences that repeat exactly. This can be accomplished by calling -randomSeed() with a fixed number, before starting the random +``randomSeed()`` with a fixed number, before starting the random sequence. - - -Parameters ----------- - -long, int - pass a number to generate the seed. - - - -Returns -------- - -no returns - - - Example ------- -:: +The following sketch initializes the random seed based on an :ref:`ADC +<adc>` reading of pin 0. If this pin is unconnected, the Sketch +should print different values to the :ref:`serial monitor +<ide-serial-monitor>` each time it is run:: long randNumber; - void setup(){ - Serial.begin(9600); + void setup() { + pinMode(0, INPUT_ANALOG); randomSeed(analogRead(0)); } - void loop(){ + void loop() { randNumber = random(300); - Serial.println(randNumber); + SerialUSB.println(randNumber); delay(50); } - - -See also +See Also -------- - -- `random <http://arduino.cc/en/Reference/Random>`_ - - - +- :ref:`random() <lang-random>` .. include:: cc-attribution.txt |