# Kindly help about Probability density function

• Oct 11th 2009, 09:35 PM
moonnightingale
Kindly help about Probability density function
Consider a signal having probability density function p(f) equals to
K exp(-|f|) for -4<f<4 and zero otherwise.

Kindly find value of K
• Oct 11th 2009, 09:47 PM
matheagle
It's an even function, so you don't need two integrals.

$.5=k\int_0^4e^{-x}dx=k\bigl(1-e^{-4}\bigr)$
• Oct 11th 2009, 10:13 PM
moonnightingale
i think it should be other way round
Thanks a lot
i think it should be like this

0.5 = K [exp(-4) -1]

What u say
• Oct 11th 2009, 10:33 PM
matheagle
Quote:

Originally Posted by moonnightingale
Thanks a lot
i think it should be like this

0.5 = K [exp(-4) -1]

What u say

NOPE

1 look over the chain rule
2 densities must be nonnegative, try calculating your k, with the math you think is correct

The derivative and hence integral of $e^{-x}$ is $-e^{-x}$