DADiSP Worksheet Functions > Function Categories > Generated Series > GRANDOM
Generates a random series based on a uniform or flat distribution. The optional range arguments let you determine the output range.
GRANDOM(length, spacing, rangelow, rangehigh)
length |
- |
An integer. The length of the output series. |
spacing |
- |
A real, the spacing (delta x) between each point of the |
rangelow |
- |
Optional. A real, the low end of the range. Defaults to 0.0 |
rangehigh |
- |
Optional. A real, the high end of the range. Defaults to 1.0 |
A series.
grandom(100,0.1,1,10)
generates a uniformly distributed random series of 100 points, spaced every 0.1 x-units, with values ranging from 1 to 10.
W1: grandom(50000, 1);label("Random Uniform")
W2: hist(w1, 30, "pdf");sety(0, 1.5);label("Histogram")
W3: gline(length(w2), deltax(w2), 0, 1);lines;overp(W2, lred);sety(0, 1.5);label("Unform Distribution")
W1 contains 50000 samples of uniformly distributed random values.
W2 contains a 30 sample normalized histogram of W1.
W2 compares the histogram to the analytic uniform distribution indicating that the random sequence in W1 is uniformly distributed.
If no range is given, default is [0,1]. If only one range is given, range is [0,range] or [range,0], depending on whether range is positive or negative.
The probability density function, f(x), for uniformly distributed random values over the interval [a,b] is:
The cumulative distribution function, F(x), for uniformly distributed random values is:
The mean is:
and the variance is:
See SEEDRAND to set a new seed value for the pseudo-random sequence.
GRANDOM can be abbreviated GRAND.