Hi Kevin,
With a Gausian distribution, the range of possible values is (-infinity,
+infinity) (the "(" and ")" mean exclusive, you can't actually get either
infinity). This is in priniciple. As implemented by the next Gaussian
function, I suppose they would be in the range of
(Double.NEGATIVE_INFINITY, Double.POSITIVE_INFINITY). Of course the
probability of getting such low numbers is very low. that's because the
distribution looks kind of like this:
***
** **
*** ***
---------------------
It's asymptotic at the ends. This means it never really reaches the base
line - it just gets closer and closer. Likewise, the chance of getting a
value "way out there" gets smaller and smaller.
- Paul
Paul Glezen
Consulting IT Specialist
IBM Software Services for WebSphere
818 539 3321
"Kevin Hammond" <[EMAIL PROTECTED]> on 11/15/2001 06:54:15 AM
Please respond to "JMeter Developers List" <[EMAIL PROTECTED]>
To: <[EMAIL PROTECTED]>
cc:
Subject: Uniform and Gaussian Timers
***** Uniform Random Timer *****
Delay = (long) Math.abs((this.random.nextDouble() * range) + delay);
The method nextDouble() returns a value between 0.0 and 1.0. So, the
minimum delay (if 0.0 is returned) is "delay", and maximum delay (if 1.0)
is
returned is "delay" + "range". We really don't need the to get the
absolute
value method call since all values are greater than zero. I would like to
change the GUI to make it easier for common people to understand the range
of delay values that JMeter will generate. Any objections?
*CURRENT GUI*
Uniform Random Timer
- Average (in milliseconds): [Text Field]
- Deviation:
*NEW GUI*
Uniform Random Timer
(Label) The total delay is the sum of "Minimum Delay" and "Uniform Random
Delay".
- Minimum Delay (in milliseconds): [Text Field]
- Uniform Random Delay (in milliseconds)
- Minimum: 0
- Maximum: [Text Field]
***** Gaussian Random Timer *****
Can someone explain this is simple terms? I ran a program that repeatedly
called the nextGaussian() method and saw values from -2.56 to 3.13. Can
someone tell me if there are min and max values that will be returned from
nextGaussian()?
Here's Sun's documentation:
public double nextGaussian()
Returns the next pseudorandom, Gaussian ("normally") distributed double
value with mean 0.0 and standard deviation 1.0 from this random number
generator's sequence.
The general contract of nextGaussian is that one double value, chosen from
(approximately) the usual normal distribution with mean 0.0 and standard
deviation 1.0, is pseudorandomly generated and returned.
Thanks!
Kevin Hammond
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