## 1201 Reputation

17 years, 197 days

## DEQ Fit...

Maple

Hi, assume  i have some data and want to fit a model function to it (Maple12). The help pages show a way:

with(Statistics):
X := Vector([1, 2, 3, 4, 5, 6], datatype=float):
Y := Vector([2, 3, 4.8, 10.2, 15.6, 30.9], datatype=float):

f:=a+b*exp(c*t);

Fit(f, X, Y, t);

It works as expected. Now assume that the model function is not explicitly given,  it may be just the solution of a  differential equation:

f:=diff(y(t),t)+u*y(t)=v; y(0)=0

## finding my roots......

Maple

Hi everyone,

i want to find the solution(s) to the following equation numerically:

f:=1+x^2+1/100*abs(ln(3-4*x))=0;

But fsolve refuses to work, it just gives the input back. Setting Digits to a stellar value didn't help, i also tried different initial points.

Thomas

## Best way to index Variables...

Maple

Hi, i have a rather basic question. Both code pieces do the same:

restart:
for i from 1 to 5 do  a[i]:=i;  end do;

a[3];

3

restart:
for i from 1 to 5 do  a(i):=i;  end do;

a(3);

3

In which case should  i use round brackets and when square brackets for indexing ?

Does it matter ?

Thomas

## mathematical induction...

Maple

Hi everyone,  to have an example, the following recurrence is given. I want to proof that it converges (and determine the limit for n->infinity).

g:=a(n+1)=3/2+sqrt(1+a(n));

Maple cannot find an explicit  form of a(n), typing rsolve(g,a(n)); gives the input back. One standard approach would be calculating the possible limit by solving the fixed point equation

a=3/2+sqrt(1+a)

this isn't a problem ofc. Further it is necessary to show a(n) is bounded and grows monotonous. So my question is, is Maple a useful tool for mathematical induction ?

## incomplete plot...

Maple

Hi,

i have a minor issue with a plot, have a look.

restart:
f:=x->piecewise(x<-1,0,x<0,-1-x,x<=1,1,0);
plot(f(x),x=-2..2,discont=true);

Where are the plot lines on the x axis for x<-1 and x>1 ?

Thomas

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