I'm trying to accent variables with both hats and checks (^ , v). I was able to get this to work using `#mover(mi("π"),mi("^"))`; but `#mover(mi("π"),mi("✓"))`; doesn't look very good. Is there a better alternative? 

This behavior by Maple is completely wrong if you ask me.

But given this is how Maple works, the question I have is how to explictly close a file opened by call to readline()?

I have a proc(), where inside it, it wants to read say first 3 lines by calling readline("input.txt") on a file. Then the proc() returns back to caller.

The first call reads the first 3 lines from the file OK.

I expected all resources to be removed after the call returns, including any files opened to be automatically closed. So next time proc() is called, I expected the first 3 lines to be read again.

It turns out the next time  proc() is called, now lines 4,5,6 are read. This is becuase the file remained open between calls!  Only way to close the file is to call restart() on the whole session. But I do not want to do this. 

Looking at help, I see no method to explicity close the file other than reading all the lines.

How does one explicitly close a file opened by readline() without reading the whole file?

Here is example

restart;

foo := proc()
local n,current_line;

   for n from 1 to 3 do
       current_line:= readline("input.txt");
       print("line read is ",current_line);
   od;
end proc;

And now the above is called as follows

currentdir("C:\\test"); #change as needed
foo()
                   "line read is ", "line 1"
                   "line read is ", "line 2"
                   "line read is ", "line 3"

Next call

foo()
                   "line read is ", "line 4"
                   "line read is ", "line 5"
                   "line read is ", "line 6"

Where input.txt is 

line 1
line 2
line 3
line 4
line 5
line 6

I know how to do all this using fopen() and fscanf() and explicit fclose(). I also know I can use FileTools package.

But wanted to check first if readline() will do what I wanted more easily if I can figure how to close the file explicitly.

Hello

I would like to fillup the area between multiple function in my plot.

The plot consist out of multiple functions. Each function connects to one another.

In total there are 10 functions that define the border. The grey horizontal lines (PL4 and PL7) and all red lines PL8 - PL15.

I tried to find codes, but i cant get them to work.

Thanks a lot for any help!

I was working through an old text book, trying to understand a different problem.  I came across this problem in an exercise set and thought it was simple.  Until I tried it.

The difficlty I had was in using subs to substitute all values.  I had to use subs 2 or 3 times to get all substitutions.  How can I avoid this?

## Prove if F is the fibonacci sequence,
restart;
with(combinat, fibonacci):
F := n -> fibonacci(n);  ## F(n+1) = F(n)+F(n-1); F(1) = 1;
## the problem
P := n-> F(n+1)*F(n+2) - F(n)*F(n+3);
##
check_low := proc(n)
    local idx;
    for idx to n do
        print(P(idx),(-1)^idx);
    end do;
end proc;
check_low(1);
check_low(2);
check_low(3);
check_low(4);

## Assume true for n=k
A := P(k) = (-1)^k;

notation := { F(k)   = a,
              F(k+1) = b,
              F(k+2) = c,
              F(k+3) = d,
              F(k+4) = e };

## some fibonacci definitions
fibs := [ e = c + d,  d = b + c, c = a + b ];

eq1 := subs(notation,A);
eq1 := subs(fibs,eq1);
eq1 := subs(fibs,eq1);  ## have to repeat to get only a and b in the expression

eq2 := subs(notation,P(k+1));
eq2 := subs(fibs, eq2);
eq2 := subs(fibs, eq2);
eq2 := subs(fibs, eq2);  ## have to repeat to get only a and b in the expression
## Reduce eq2 to (-1)^(k+1)
simplify(eq2 = -lhs(eq1));
verify(eq2, -lhs(eq1), equal);
evalb(eq2); simplify(%);  ## Ah, this is why I need equal in verify.
evalb(-lhs(eq1)); simplify(%);

testeq(eq2, -lhs(eq1));

Hi, 

Suppose you have to do some sequence of operations on a random variable (RV), and that you need to repeat this for several RV of the same family (e.g. exponential RV), differing only in the values of their parameters.

Here are two examples do code this.
1/ probably the most natural way to proceed (?)
restart:
with(Statistics):
X := a -> RandomVariable(Exponential(a)):
for n from 1 to 100 do
  S := X(n);
  # here are some operations to do
end do:
anames(alluser);
The last instruction indicates that 103 user variables have been created (X, n, S and 100 random variables).
Note that adding one of the commands S := 'S'; or unassign('S') before the end of the loop just unassigns S but not remove the variables named _ProbabilityDistribution, ..., _ProbabilityDistribution98.

2/ To prevent this inflation of random variables I thought to use the procedure Specialize:
restart:
with(Statistics):
X := RandomVariable(Exponential(a)):
for n from 1 to 100 do
  S := Specialize(X, [a=n]):
  # here are some operations to do
end do:
anames(alluser);
This doesn't change the situation.

So my (multiple) question: 

• How can I prevent the creation of the objects _ProbabilityDistribution, ..., _ProbabilityDistribution98 given only one of them is used for a given value of the loop counter (once the operations have been done I pass to another random variable) ?
• How can I unassign a random variable ?
  Maybe it is not possible as suggested by the help page about "_": "Any symbol beginning with an underscore (_) is effectively reserved for use only by library code. It is not available to users." ?

Thanks in advance

Hello everyone,

I have the following problem:

I have an array of data dataarray[i,j,k] whose elements are either 1 or -1. I also have three vectors x[i], y[j] and z[k] (the axis).  I want to represent the data of dataarray so I have two different volumes: A green volume such as dataarray(x,y,z)=1 and a red one with dataarray(x,y,z)=-1. Is that possible? In case that it is, how can I do that?

Thank you very much in advance

Hi!

I am trying to determine the weights of a Gauß quadrature rule, the code I currently have is this:

for i from 1 to n do
  RekursivesZwischenergebnis:=1;
  for j from 1 to n do
    if i <> j then
      RekursivesZwischenergebnis:= RekursivesZwischenergebnis*((x-GaußKnoten[j])/(GaußKnoten[i]-GaußKnoten[j]))
    end if;
  end do;
  GaußGewichteAlt[i]:=int(RekursivesZwischenergebnis,x=-1..1);
end do;
 

The code works, is inefficient however. I want to use the product or mul function, however I dont know how to tell Maple not to multiply

((x-GaußKnoten[j])/(GaußKnoten[i]-GaußKnoten[j]))

if j=i.  mul(function(j), j=1..n,j<>i) doesnt work. Any efficient suggestions?

Hello,

I'm compiling a maple procedure to a C code with the Compiler command. I was wondering if it is possible to change the optimization flag, for example -03  for gcc? Is there a way to maybe change a file in the Maple directory that specifies the compiler options?

with(IterativeMaps): with(ImageTools):

BP := proc(f, S, I, m, M, xm, xM)
    local L;
    L := Bifurcation([x], f, S, m, M, xmin=xm, xmax=xM, height=800, width=1300, iterations=I+500):
    ArrayTools:-Dimensions(L):
    ColouringProcedures:-HueToRGB(L):
    Embed(L);
    L:    
end proc:

F := []:
f := [sign(r)*ln(abs(r))*cot(x)*(log[2+abs(r)](abs(x)) - x*sin(x))]:

F := [op(F), BP(f, [0.1], 10000, -10, 10, -15, 15)]:
F := [op(F), BP(f, [0.2], 10000, -10, 10, -15, 15)]:

F := [op(F), BP(f, [0.3], 10000, -10, 10, -15, 15)]:

F := [op(F), BP(f, [0.4], 10000, -10, 10, -15, 15)]:

I was trying to create some images of some bifurcations. I can't seem to create an animation from the images.

Also, Embed works great but each call to BP overwrites the previous image(rather than creating a new image)... Preview works but doesn't scale the images up properly.

How can type limit proc() and use print to export expression as mathtype?

Download help_limit.mw

I was reviewing the StringTools features and I'm curious about some parts of it.

(1)     Here is a section from the StringTools[Length] help topic:

Hello,

I have installed Maple 2020 and I tried some examples of the new capabilities of command is:

restart;
is(0 <= (a - b)^2 + (c - d)^2) assuming real;

It gives FAIL instead of true,

Similarly the simpler example

is(x = 0) assuming (0 < abs(x));

also gives FAIL incorrectly.

Perhaps, does this problem relate to a problem with calling SMTLIB package?

Best Regards,

Here is the deal, I made a programm so as to display the curve of a ping pong ball. But Maple isn't able to solve the 3 ODE system analytically. I then decided to make Maple solve them numerically and it actually works, great. However, there's still a big problem : how can I display the graph of the solutions ? I'd like you to give your opinion on a way to solve the problem. Thanks ;) 
 

Download programme_de_calculs.mw

Hi

I want to employ FDM to solve nonlinear ODE. Since large expressions in terms of s[1] are generated, the program lose its efficiency for N>6 (It requires long run-time). Please amend the program, if it is possible to reach more precision for N>10. Moreover, is there a Maple command to dsolve this ode?

Thanks alot

restart;

sy := 2400.:

Hp := 0.1e9:

P := -900.:

a := 20.:

c := 21.:

N := 6:

s[0] := P:

h := (c-a)/N:

Et := (r*(diff(sr(r), r))-sy)/Hp:

Er := (sy-r*(diff(sr(r), r)))/Hp:

ode := simplify(Er-Et-r*(diff(Et, r))*(1+(diff(Et, r))*r/(2+4*Et))):

ode:=subs(diff(sr(r), r, r) = (s[k+1]-2*s[k]+s[k-1])/h^2, diff(sr(r), r) = (s[k+1]-s[k-1])/(2*h), r = h*k+a, ode):

for k to N-1 do

s[k+1] := solve(ode, s[k+1])[1]

end do:

s[1] := fsolve(s[N] = -200., s[1] = -900 .. -100);

plots[pointplot]([seq([h*k+a, s[k]], k = 0 .. N)]);

Hi, i have accelerometer readings saved as a CVS file., these file contains time data, then the accelerometer data in g's. (recorded at 700hz)

I need to analyse the data for hand-arm vibration and be able to plot the frequency/time. 

i have managed to fft the data but im struggling to plot this.

thanks for the help!!!