For instance, given nine integer x₁, x₂, …, x₉ satisfying x₁, x₂, …, x₉ ≥ -5 and x₁³＋x₂³＋…＋x₉³＝0, the goal is to maximize x₁ + x₂ + … + x₉. However, according to Optimization/Options,  is not accepted by the Optimization:-Maximize command. A probable method is applying floor into the optimization variables; unfortunately, I can only get: Error, (in Optimization:-NLPSolve) no improved point could be found. 

(*restart;*)
vars := [x || (1 .. 9)]:
Optimization:-Maximize(`?()`(`+`, floor~(expr)), [add(floor~(expr) ^~ 3) = 0, expr[] >=~ -5], initialpoint = (unapply~(expr) =~ rand(-5 .. 10))()); # Alternatives to exhaustive search?
Error, (in Optimization:-NLPSolve) no improved point could be found

Is there any workaround to solve this problem? 

I am trying to find a polygon that its graph take this four points as extra point. 
I tried
f := x -> a*x^7 + b*x^6 + c*x^5 + d*x^4 + k*x^3 + l*x^2 + m*x + n;
solve([f(-2) = -5, f(5) = -6, f(6) = 1, f(-1) = 2, eval(diff(f(x), x), x = -2) = 0, eval(diff(f(x), x), x = 5) = 0, eval(diff(f(x), x), x = 6) = 0, eval(diff(f(x), x), x = -1) = 0], [a, b, c, d, k, l, m, n]);

I get. Is there a polymial with lower degree take this four point as extra points?

how I can plot phi[2] as a contour like attached figure?

tez-1.mw

Download tez-1.mw

Download tez-1.mw

Please, is there anyway I can solve below problem without replacing the Alpha with value? The error I got is "Error, (in fracdiff) Unable to determine ceiling of alpha"

>

>

>-fracdiff(U1, t, alpha)+U1/M-U1^2/(M*K)+diff(U1, t)-(diff(U1, t))/epsilon

>int(%, t)

Dear all
Warm Greetings.

I want to display a solution (only numerical value) of the first derivative of the function for the values of x varies from 0 to 7 with step size 0.01.

I have attached the work file. 
ODE.mw

Please do the needful.

Thanks in advance.

Hi dear Users!

I hope everyone here is fine. I have a function like

f := exp(-t)*(x^2-5*x^3+10*x^5+x+3+.5*x^4)+(1/2)*x^2*(x-1)+2*sin(x);

I have to find the value of t at which the behavior of this function is constant for 6 decimal places against x from 0..1. This is my effort

restart;
N := 20; TOL := 10^(-6); Points := 100000;
f := exp(-t)*(x^2-5*x^3+10*x^5+x+3+.5*x^4)+(1/2)*x^2*(x-1)+2*sin(x);
for j from 0 while j <= 10 do print("\nWhen x = ", j/(10.));
for i from 0 while i <= Points do
g[i, j] := evalf(eval(f, [x = (1/10)*j, t = N*i/Points]));
if `and`(i >= 1, abs(g[i, j]-g[i-1, j]) < TOL) then print("Value of t = ", evalf(N*i/Points)); print("Value of f = ", g[i, j]); break else  
end if end do end do;

The same value is then verified by making graphs

plot([eval(f, t = 1), eval(f, t = 2), eval(f, t = 3), eval(f, t = 4), eval(f, t = 5), eval(f, t = 6), eval(f, t = 7)], x = 0 .. 1, color = [red, green, blue, cyan, yellow, black, purple]);
plot(eval(f, x = .8), t = 0.1e-1 .. N);

Here I want to know if is there any more effective maple command to find the value of t rather than using procedures (highlighted by red) or a graphical way.

I have been trying to to get a loop to sum the elements of a list of n size, and then take a certain element of summen list (which meets) a certain condition. And then print it out. 

What I can get it to do is printing the input list, and summing the elements in a new sister list sequence. And then if I for instance want its to print the element in testseq which is less than 15. Then it instead prints all elements less than 15 in testseq. What I would like to do is to move the index, so it only prints 10 and save it to a constant? 

So what am I missing?

test := [1, 2, 3, 4, 5, 6, 7, 10];
               test := [1, 2, 3, 4, 5, 6, 7, 10]

testseq := [seq(sum(test[i], i = 1 .. j), j = 1 .. numelems(test))];
            testseq := [1, 3, 6, 10, 15, 21, 28, 38]

for i to nops(test) while testseq[i] < 15 do
    testseq[i];
end do;
                               1

                               3

                               6

                               10

Is it possible to use the Maple command timelimit(time, procedure(.......)) inside a loop of the type "for j                     do        procedure(.......)                   end do" without getting the error 'time expired" that forgets that value of j and  continue with the next value of j. How?

Is it possible in Maple Flow to reference to another worksheet as you can in Maple? If so, how would you do that? Thanks in advance for your help.

I'm attempting to visualize temperature averages across a 2 dimentional space (e.g., a square plate) with fixed heat sources. The 3rd dimension (z axis) represents temperature.  I have created several visualizations but have questions about how these plots work.  The model is attached and the questions will make sense once you open the worksheet.

1. Using the "colorscheme" option on a couple of matrixplots, I get the error "[Length of output exceeds limit of 1000000]" and the plot doesn't show.  However using the "display()" command on those same plots does render the plot.  Is there a way around this error (i.e., rendering the plot directly) or should I just suppress the error using a colon at the end of the plot statement and rely on display() to show the plot?
2. I've created a heat map as one of the visualizations.  Is there a way to access the color values at each of the "cells" of the heat map? I would like to use these colors elsewhere in the model but I'm not sure if there is a way to access the color values.
3. Using a 3D point plot as one of the visualization options, I use the colorschemes with options "xgradient", "ygradient", and "zgradient".  For some reason, "xgradient" and "ygradient" work as expected but "zgradient" looks the same as "ygradient".  How do I get the color transition to change along the z axis rather than only x and y axes?

Thank you for your help on these questions.

temperature_profile_(experimental)(v01).mw

According to Maple help, the plots:-display function can be called with parameter (P).

P - a set, list or Array (one- or two-dimensional) of plot structures, or an animation structure

Both in the last section of the help function, and code in this example (https://mapleprimes.com/questions/236270-Plot-Objects-Created-Created-With-Geometry), it apparently can be called differently.

• display(A, B, view = [-3*Pi .. 3*Pi, -1 .. 1])
• display(F, draw(B))

A, B or F, draw(B) er graphics objects, but the call format is neither a set, list or Array.

Is the explanation for plots:-display incorrect, or am I missing something here?

Hi,
I have a function "w" that the eval command does not gives the correct value of its first derivative at a fixed point. I guess the problem is due to sqrt() terms, but I can't fix it. 
eval.mw

Hello everyone! I have found this document from Maple 18 (2014) that will be very usefull for my school work, but when i copy it into Maple 2022 i get the error message, "action, does not evaluate to a module" Is there any way for me to fix this? What i have been able to read is that i have to go in and update the code, but i have absolute no idea on how to do it? 

Kind Regards Samuel 

Regressionmodeller._Skal_laves_til_maple_22_og_23.mw

How can I plot stream lines between two concentric spheres?

Hi,

I am using Maple 2020 to numerically solve/generate numerical plots for my impulsive control problem.

The optimal control problem is:

T is time from0 to T where T is the terminal time

K(t), B(t) and M(t) are state variables

w(t) is a control variable

a(ti) is the impulsive control variable at time ti,

a(ti) \in [0,1] for i=1,2,…,N

ggamma, ttheta, ddelta1, ddelta 2, c1 and c2 are constants

K(T)=M(T)=0 B(T)>0

K'(t)=ggamma*K(t)*w(t)-ttheta*M(t)

B’(t)=ggamma*K(t)+ttheta*M(t)*B(t)

M’(t)=M(t)-ggamma*w(t)

M(ti)=M(ti-)+a(ti)M(ti)*ddelta1

K(ti)=K(ti-)-a(ti)K(ti)*ddelta2

Objective: maximize B(T)-integral from 0 to T of c1*(w(t))^2dt-sum i=1 to N of c2*a(ti)

Here is the code I enter to MAple:

restart;

# Define the constants
ggamma := 1.0;
ttheta := 2.0;
ddelta1 := 0.1;
ddelta2 := 0.2;
c1 := 0.5;
c2 := 0.3;
T := 5.0; # Terminal time

# Define the impulsive changes in M(t)
impulse_changes := proc (t)
    local ti_values, imp_values, result;
    ti_values := [1.0, 2.0, 3.0]; # Example impulsive time instants
    imp_values := [0.2, 0.1, 0.3]; # Corresponding impulsive control values
    result := 0;
    for i from 1 to nops(ti_values) do
        if t = ti_values[i] then
            result := result + imp_values[i]*M(ti_values[i])*(ddelta1 - ddelta2);
        end if;
    end do;
    return result;
end proc;

# Define the system of differential equations
diffeqs := {diff(K(t), t) = ggamma*K(t)*w(t) - ttheta*M(t),
            diff(B(t), t) = ggamma*K(t) + ttheta*M(t)*B(t),
            diff(M(t), t) = M(t) - ggamma*w(t)};

# Define the impulsive controls
impulse_controls := [1.0, 0.5, 0.8]; # Example impulsive control values

# Define the initial values and conditions
initial_values := [K(0) = 0, B(0) = 0, M(0) = 0];

# Define the final conditions
final_conditions := [K(T) = 0, M(T) = 0, B(T) > 0];

# Define the objective function to be maximized
objective := B(T) - int(c1*w(t)^2, t = 0 .. T) - add(c2*impulse_changes(ti), ti = 1.0 .. 3.0);

# Solve the system of differential equations numerically
sol := dsolve({diffeqs, initial_values, final_conditions}, numeric, output = listprocedure);

# Find the optimal control trajectory w(t) using optimization
w_optimal := optimize(objective, numeric, maximize);

# Evaluate the optimal control and state trajectories
optimal_controls := [seq(w_optimal(t), t = 0.0 .. T, 0.1)];
state_trajectories := [sol[2](t), sol[3](t), sol[4](t)];

optimal_controls, state_trajectories;

I am getting the error:

"Error, (in dsolve/numeric/process_input) system must be entered as a set/list of expressions/equations"

as soon I run after the sol:= function.

I would appreciate any help with fixing my code!

Thank you very much!