Maple supports many special mathematical functions including all of the trigonometric, exponential, logarithmic, Bessel, Dirac, Gamma, and polynomial functions. There is not enough space to cover all of them here, but we will go through a number of examples.
You have already seen several examples of trigonometric, exponential, and logarithmic functions, but here are some more:
> F:= x ->(arcsin(x)-tan(x))/(x*sin(x)+cos(2*x));
arcsin(x)- tan(x)
F := x ->-------------------
x sin(x) +cos(2 x)
> evalf(F(2*Pi));
1.570796327 -2.524630660 I
> G := x -> 2*x*exp(x))/log10((3*x^2)/(x-5)^3);
x exp(x)
G := x -> 2 -----------------
2
x
log10(3 --------)
3
(x - 5)
> G(1);
exp(1)
2 ------------
log10(-3/64)
> evalf(");
5.436563656
--------------------
log10(-.04687500000)
Now let us look at some special functions.
Bessel functions are a common form of
equation. Maple supports Bessel functions of
the first and second kind and modified Bessel
functions of the first and second kind. Let
us compute the value of a fourth order Bessel
function (J) of the first kind with
x=9.6. We shall use the
BesselJ command:
> BesselJ(4,9.6);
-.2632581481
Why not plot the entire function from -10 < x < 10?
> plot(BesselJ(4,x),x=-10..10);
AAAA 0.4 + AAAA
AA AA + AA AA
A AA + AA A
AA A 0.3 + A AA
A AA + AA A
A A + A A
A A 0.2 + A A
AA A + A AA
A AA + A A
A AA 0.1 + AA A
A AA + AA A
AA AAA + AA A
+---+--+-*-+---+--+---+---+---***************---+---+---+--+---+-*-+--+---+
A 0 + A
-10 A -5 0 5 A 10
A + A
A -0.1 + A
A + A
A + A
A AA -0.2 + AA A
AA AA + AA AA
AAAA + AAAA
The Gamma function is defined as follows:
> G:=t->int(t^(n-1)*e^(-t),t=0..infinity);
infinity
/
| (n -1) (- t)
G := t -> | t e dt
|
/
0
where n > 0
We can plot the discontinuous Gamma function directly without having to define it first:
>plot(GAMMA(t),t=-10..10,-10..10,discont=true);
AA 10 * A
AA * A
AA * A
AA *A A
AA *A A
AA 5 *A A
AA A *A AA
AA AA *A AA
AA A A *AA AA
AA A A * AAA AAAA
*****--******--*****--+***+---**-*---*---+**+---+---+---+--+---+---+--+---+
AAA AAA AAAA A A A 0 *
-10 -5 AAA A A 0 5 10
A A A A *
A A A A *
AA A AA*
A -5A*
A AAA*
A A*
A A*
*
-10 *
We can automatically derive various orthogonal
polynomials with the
with(orthopoly) command:
> with(orthopoly);
[G, H, L, P, T,U]
We can now easily a third order Hermite polynomial and a ninth order Laguerre polynomial with 2x-a+b as a variable, to name two:
> H(3,x);
3
8 x - 12 x
> L(9,2*x-a+b);
2 3
1 - 18 x + 9 a - 9 b + 18 (2 x - a + b) - 14(2 x - a + b)
4 21 5 6
+ 21/4 (2 x - a + b) - ---- (2 x - a +b) + 7/60 (2 x - a + b)
20
7 8 9
- 1/140 (2 x - a + b) + 1/4480 (2 x - a+ b) - 1/362880 (2 x - a + b)
Sometimes special functions hit us when we least expect them to:
> K:= u -> int(exp(-u^2),u);
/
| 2
K := u -> | exp(-u ) du
|
/
This looks okay, but what happens when we try to evaluate this equation?
> int(exp(-u^2),u);
1/2
1/2 Pi erf(u)
This result called up the standard error function, erf(u):
> error:=x-> ( 2 /sqrt(Pi) ) *int(e^(-u^2),u=0..x);
x
/ 2
2 | (- u )
error(x) = ------- | e du
sqrt(Pi) |
/
0
Maple will just pass the value of this equation on in all of its calculations. Of cource, we can plot this function, easily:
> plot(erf(u),u=0..5); 1 + AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA + AAAAAA + AAA + AA 0.8 AA + AA + AA + A 0.6 AA + AA + AA + A + A 0.4 A + A + A + A 0.2 AA + A +A * *--+--+--+--+--+--+--+--+--+--+--+--+-+--+--+--+--+--+--+--+--+--+--+--+--+ 0 0 1 2 3 4 5
For more of Maples capabilities with special functions, please look at the resources page at the end of this tutorial.
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