## 245 Reputation

1 years, 308 days

## Belousov–Zhabotinsky equation ...

Maple

Hi! Do you know maybe how to solve equation with Laplace operator in Maple like BZ equation?

restart;
a := 0.75;
rho := u(t) + v(t) + w(t);
ode := diff(u(t), t) = 10*Delta(u(t)) + u*(-a*v - rho + 1);
ode1 := diff(v(t), t) = 10*Delta(v(t)) + v*(-a*w - rho + 1);
ode2 := diff(w(t), t) = 10*Delta(w(t)) + w*(-a*u - rho + 1);

Edit: Sorry I guess it should be function of three variables so u,v,w depends on (x,y,z) not strictle from time

I am wondering how to animate something like this from BZ equation:

## Area under dataset...

Maple

Hi! do you know any effective method to count area under this function given by dataset points? (I counted this by approximation by trapezes)

Edit: PolyFit is ok the best what I have done

Edit2: triangulation is the best (just add all triangles)

## How to divide array?...

Maple

Hi! Do you know how to divide this array from .txt data to take separately these numbers? (I have over one thousands of these so I don't want to rewrite)

PS this is 1x1 I want to make 1x8

["0,00244140625;8,07751097960625;-3,555908203125E-05;0,002166748046875;1;1;0,0056941700604248;-0,0101856454842773;100 µA"]

## Bad odeplot and getting back function fr...

Maple

restart;
g := 9.81;
with(DEtools);
with(plots);

odeplot(dsolve({diff(x(t), t, t) = 0, diff(y(t), t, t) = -g + y(t)^2, x(0) = 1, y(0) = 0, D(x)(0) = 0, D(y)(0) = 0}, numeric), numpoints = 1000);

Hi, do you know why this plot is ragged? and my second question do you know how to get a single function x(t) or y(t) from this numeric solution instead getting parametrization plot [x(t),y(t)]? Thanks in advance.

## How get plot of a function from the nume...

Maple

restart;
with(plots);
g := 32.2;
k := 0.1;
theta := Pi/5;
v := 50;

ode0 := diff(x(t), t \$ 2) = 0, diff(y(t), t \$ 2) = -g

ode1 := diff(x(t), t \$ 2) = -k*diff(x(t), t) - x(t) - 1/6*x(t)^3 + 1/120*x(t)^5, diff(y(t), t \$ 2) = -g - k*diff(y(t), t) - y(t) - 1/6*y(t)^3 + 1/120*y(t)^5

ics := x(0) = 0, y(0) = 0, D(x)(0) = v*cos(theta), D(y)(0) = v*sin(theta)

dsolve([ode1, ics], numeric)

dsolve([ode0, ics])

display(plot([rhs(dsolve([ode0, ics])[1]), rhs(dsolve([ode0, ics])[2]), t = 0 .. 2], color = red), plot([rhs(dsolve([ode1, ics, numeric])[1]), rhs(dsolve([ode1, ics, numeric])[2]), t = 0 .. 2]), view = [0 .. 75, 0 .. 15])

Hi! Do you know maybe how to get this plot of ode1? I guess that computations are ok but I cannot get this plot.

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