# pdfexp, cdfExp

0

i´m lost in the use of pdfExp(x,a,m), cdfExp(x,a,m). Given that the exponential is iqual to:

What are the location and mean parameter?

For the cdfexp you said that it´s iqual to:

qthelp://aptech.com.gauss.13.0/doc/Equation40.png

I don´t see any m there?

How can I have the same values than Matlab whith his expcdf and exppdf functions?

Thank you.

0

The pdfExp and cdfExp in GAUSS calculate the two parameter exponential function. This is documented more clearly and accurately in the latest version of GAUSS.

For easy comparison, I will show a few different parameterizations in GAUSS code. First, the single-parameter exponential function with a rate parameter called lambda. This is the one which you posted above.

val = lambda * exp(-lambda * x);


Second, the single-parameter exponential function with a scale parameter beta. This scale parameter is the reciprocal of the rate parameter.

val = (1/beta) * exp(-x/beta);


Finally, the two-parameter exponential function with a scale parameter beta and a threshold parameter (or location parameter in a sense) theta. This is the function in GAUSS.

val = (1/beta) * exp(-(x - theta)/beta));


To calculate the single-parameter exponential function in GAUSS, you will always set the second input equal to 0. If you are thinking of the distribution in terms of the rate parameter, lambda then you will pass in the final value as the 1/lambda. Here are some examples:

//x = 1.2, lambda = 0.5
val_1 = 0.5 * exp(-1.2*0.5);

//x = 1.2, beta = 2
val_2 = 1/2 * exp(-1.2/2);

//x = 1.2, beta = 2, theta = 0
val_3 = 1/2 * exp(-(1.2 - 0)/2);

//x = 1.2, beta = 2, theta = 0
val_4 = pdfExp(1.2, 0, 2);


For each of these the answer should be: 0.27440582.

aptech
342

• ### Aptech Systems, Inc. Worldwide Headquarters

Aptech Systems, Inc.
2350 East Germann Road, Suite #21
Chandler, AZ 85286

Phone: 360.886.7100
FAX: 360.886.8922

• ### Training & Events

Want more guidance while learning about the full functionality of GAUSS and its capabilities? Get in touch for in-person training or browse additional references below.

• ### Tutorials

Step-by-step, informative lessons for those who want to dive into GAUSS and achieve their goals, fast.

• ### Have a Specific Question?

Get a real answer from a real person

• Need Support?
• ### Support Plans

Premier Support and Platinum Premier Support are annually renewable membership programs that provide you with important benefits including technical support, product maintenance, and substantial cost-saving features for your GAUSS System or the GAUSS Engine.

• ### User Forums

Join our community to see why our users are considered some of the most active and helpful in the industry!