Family of density functions in R

There is a family of density functions in R. Their names follows this pattern:

d<distribution name>

For example: dnorm, dbinom etc.

Now when do we need such functions?

Whenever

• you know your target distribution and 
• you know its distribution parameters and 
• you want to know the probability of occurrence of an input.

For example

• you know that it is Normal distribution and
• you know that its Mean is 0 and SD is 1 and
• you want to know the probability of occurrence of -0.5555556 then
• invoke dnorm(c(-0.5555556),mean=0,sd=1)

Nice.