# Exponential Decay Calculator and Grapher

This is an online grapher for exponential decay functions of the form

a(t) = A e- r t

where A is the initial amount (or population), r is the rate of decrease and t is the time.
Exponential decay functions are very important as they are used to model situations in physics, chemistry, eletricity, economics...; hence a thorough understanding of this class of functions is necessary for their proper use in the listed fields of applications.
To gain better understanding of exponential decay functions, we need to compare two or more of these functions with different parameters A and r. One way to understand the effect of each of the two parameters is to fix one of the parameters, r for example with r1 = r2, and assign different values to A1 and A2 which will make it easy to understand the effect of A.

## How to use the Exponential Decay Calculator and Grapher

The purpose of this grapher is to deepen the understanding of exponential decay functions by comparing two functions with different parameters. Enter initial amount A1 and the rate of decrease r1 (positive) for the first function a1(t) and the amount A2 and rate of decrease r2 (positive) for the second function a1(t) then press the button "Graph". Time t is also an interval of time starting from zero.

a1(t) = A1 e- r1 t :      A1 =          r1 =
a2(t) = A2 e- r2 t :      A2 =          r2 =
Time Interval = Seconds

Hover the mousse cursor on the graph to read the value of the time t and the y coordinate which is equal to the value of the function a(t).
Hover the mousse cursor on the top right of the graph to have the option of download the graph as a png file.

Exponential Functions.
Graph of Exponential Functions.