Returns the base of the natural logarithm e raised to a power a, i.e. ea.
Syntax
EXP(Value)
Input
Value | is the exponent to which e is raised |
Domain type: | any Value domain |
Output
EXP returns: | a real value |
Domain: | system domain Value |
Value range: | >0 |
Notes:
Tips:
Usable in
MapCalc, TabCalc, Simple calculators
Examples
Pocket line calculator examples:
? EXP(1) |
returns 2.7183 |
? EXP(SQ(2)) | returns 54.5982 |
MapCalc example:
OutMap = EXP(InMap)
InMap |
OutMap |
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|
|
TabCalc example:
OutCol = EXP(InCol)
InCol |
OutCol |
2.0 |
7.3891 |
1.0 |
2.7183 |
0.5 |
1.6487 |
0.2 |
1.2214 |
0.0 |
1.0000 |
-1.0 |
0.3679 |
? |
? |
-0.4 |
0.6703 |
-0.1 |
0.9048 |
Applied example: exponential growth functions
In general, an exponential growth function is defined as:
An = A0 * eperc/100*n
where:
An |
is the amount after n years |
A0 |
is the amount in year 0 |
perc |
is the growth rate as a percentage per year |
n |
is the number of years |
In ILWIS this function looks like:
An = A0 * EXP(perc/100*n)
The expected total residential area after 4 years, of a residential area of 1136 ha with an estimated growth rate of 6% per year, is:
1136 * EXP(6/100*4) = 1444
For the other landuse areas the results are:
LandUse |
AreaHaY0 |
GrowPerc |
AreaHaY4 |
Residential |
1136 |
6 |
1444 |
Commercial |
116 |
2 |
126 |
Industrial |
173 |
3 |
195 |
Institutional |
137 |
1 |
143 |
Recreational |
77 |
2 |
83 |
Transportation |
18 |
1 |
19 |
Where:
Column AreaHaY0 contains the areas in hectares for each land use class in year 0.
Column GrowPerc contains growth rates per year.
Column AreaHaY4 contains the areas of the land use classes after 4 years.
Notes:
See also: