Questions tagged [constraint]
The constraint tag has no usage guidance.
133
questions
2
votes
2answers
176 views
Draw a (1/4) partial 3D cylinder in a quadrant
Here is a code to draw a full cylinder $\theta \in [0, 2\pi)$:
Graphics3D[Cylinder[{{0, 0, 0}, {1, 0, 0}}, 1/2]]
My question is that how do we draw a 1/4 of the cylinder, such that it only appears in ...
0
votes
0answers
36 views
Generating iteration and constraint lists dynamically
I have a model for which I want to perform a set of calculations with successively deeper iterations and more constraint. In other words for a given value of a Do iterator, n, I want to:
perform a ...
0
votes
1answer
126 views
Equation of motion through the Lagrangian with Lagrange multipliers
I ask for advice, I'm a little confused. I have such a Lagrangian.
$L=\frac{1}{2}m(\dot{x}^2+\dot{y}^2)-\lambda(2x^2+3y^2-1^2)$
Here $\lambda(2x^2+3y^2-1^2)$ is the constraint on the phase variables.
...
3
votes
2answers
74 views
How do you make two interactive sliders dependent on eachother?
I have this code.
Definition of q is:
...
2
votes
1answer
50 views
use of parametric ndsolve with a constraint
I want to solve differential equation
$$ \frac{y''[x]}{(1+y'[x]y'[x])^{3/2}} = -a -y[x]/ \sqrt{2} + x/ \sqrt{2} $$ subject to boundary condition $y(-1) = y(1) = 0$ for some value of $a$. $a$ is found ...
0
votes
0answers
32 views
Matrix modification with constraint on it
$q$ is a real antisymmetric matrix and can be defined as:
...
3
votes
2answers
106 views
Creating a matrix of dimension d with constraints on indices
Is there a way to create a matrix $q$ of dimension $d$ with constraints on the indices given by:
$$d\longrightarrow dimension$$
$i,j $ are indices
$$q_{i,j}=\begin{cases}
-b & j=i+d,\\
c & j=...
1
vote
1answer
54 views
How to enforce constraints on matrix equations for unknowns to have only one non zero element per row?
I am trying to find a nice and efficient way to approach the following problem:
I need to solve (for example using Solve, Reduce, or NSolve) certain type of equations involving a set of unknown square ...
0
votes
1answer
53 views
Maximization under constraints / find maxima
I am trying to code the following maximization program that I am not able to solve algebraically (Of course I manage to get the first derivative, but struggle finding its root):
$\begin{equation} Max_{...
1
vote
0answers
37 views
Find the ratio of two volumes of 6 x 6 positive-definite symmetric matrices
Consider the class $A$ of $6 \times 6$ positive definite matrices with real entries and unit trace (that is, the sum of the six diagonal entries is 1). (In quantum information-theoretic parlance, this ...
1
vote
1answer
58 views
Control evaluation for functional constraints
I'm trying to understand how to use Mathematica to find a solution subject to constraints, where one of the constraints is specified as a predicate function. But I don't know how to control evaluation ...
0
votes
0answers
54 views
Construction of Navigation Function: Error
https://en.wikipedia.org/wiki/Navigation_function
https://www.sciencedirect.com/science/article/abs/pii/S0921889015302451
https://arxiv.org/pdf/1605.00638.pdf - Paragraph III
I am trying to create a ...
0
votes
2answers
101 views
listing of vectors satisfying some special constraint
We have
list = {{1, 1, 0}, {1, 0, 1}, {0, 1, 1}, {-1, 1, 0}, {1,-1, 0}, {-1, -1, 0}, {-1, 0, 1}, {1, 0, -1},{-1, 0, -1},{0, -1, 1},{0, 1, -1},{0, -1, -1}}
...
2
votes
2answers
117 views
FindMinimum with constraint produces incorrect results
Issuing the following:
FindMinimum[{x, ((2 x + 1)/(3 x - 2))^(4 x - 3) <= 10^-10}, {x, 2}]
produces a value of 13.1686 . The constraint for that value is: 1....
1
vote
3answers
125 views
Maximize - Non binding constraint is changing the result
When I add a non-binding constraint to a maximization problem the result changes. I don't understand why.
Below you can find the code that I am using.
For the maximization A, H = 6837.66
For the ...
2
votes
1answer
60 views
In NMinimize, how to incorporate constraints on positive semidefiniteness of a matrix which is not the matrix variable being optimised?
The problem
I want to solve the following problem for symmetric matrix $X$:
$$
\begin{aligned}
\min_{X\succ 0} \; & -\log(\det(X)) & \\ \text{subject to} \; & \begin{pmatrix} X &...
2
votes
2answers
71 views
Calculate the Viswanath's constant (Random Fibonacci sequences)
How Can I calculate first few digits of Viswanath's constant?
Viswanath’s constant ≈ 1.1319882487943 is a real number whose nth power approximates the absolute value of the nth term of some random ...
0
votes
0answers
45 views
Constraints and Tolerance
So I'm running NMaximize for optimizing a value and for constraints, I need the parameters to belong to a discrete set of elements. Basically, the constraint looks ...
0
votes
1answer
67 views
How to find a numerical solution for a differential equation with constraints?
I want first to apologize for my poor english level ^^ Let me present my issue.
I want resolve numerically (I use Python) for x in [0;1] the following differential equation : $$dy/dx = a(y - y^2) $$
...
2
votes
1answer
106 views
Verify a conjectured formula for a modification of a 3D constrained integration successfully solved using Mathematica
I've acquired somewhat indirect--and not fully conclusive--evidence that the solution of a certain three-dimensional constrained integration takes the form
...
1
vote
1answer
32 views
Plotting 3D region depending on 2 parameters with constraints
I'm trying to plot the full range that a set of estimates gives. They depend on some parameters and conditions, but I haven't been able to to it effectively with RegionPlot3D. Here is the set that I ...
0
votes
0answers
35 views
Bug with ValueQ involving fractions? [duplicate]
Expected behavior:
ClearAll[f];
ValueQ[f[1]]
False
Unexpected behavior:
...
0
votes
1answer
98 views
Find the probability (relative volume) of a certain 4-ball with respect to Hilbert-Schmidt measure
Let us consider the set of points {x,y,z,1-x-y-z} and impose the strict ordering constraint
...
2
votes
1answer
100 views
Solving an equation with a constraint involving not-equal
I am trying to solve an equation with a constraint involving not-equal.
For example:
$2 x + 3 y = 5$ with the constraint $2 x + 4 ≠ 2$.
How should I approach this?
Edit 1
I tried the suggestions in ...
1
vote
2answers
178 views
Confirm and possibly simplify a 2009 result for a 2D constrained integration
This is a direct descendant of two other recent questions,
3D and Equivalence,
both of which have been
answered in skillful, interesting manners. (See also the comment [actually answer] of JimB to
...
1
vote
1answer
74 views
How to force LinearModelFit to return Non-negative coefficients?
LinearModelFit[{m,v}] will return a coefficients list $\beta$ from the design matrix $m$ and response vector $v$, where $m.\beta$ is fitted to $v$. However, the ...
0
votes
2answers
52 views
FindMaximum under binary constrains
I'm trying to find a maximum for a function whose variables have binary values (either -1 or 1). The clumsy code for that constraint I use is shown below. There must be a more compact code, and I ...
2
votes
3answers
367 views
Evaluate a certain three-dimensional constrained integral
The result of the three-dimensional integration
...
3
votes
0answers
61 views
How to generate a large number of constraints for all indices ($\forall i$)
Is it possible to generate a set of constraints in the form "$\forall$".
For example:
\begin{align}
\min\ & f\left(\sum x_i\right)\\
s.t.\ & \\
& x_i\geq 17 && \forall i=...
2
votes
1answer
131 views
Solving symbolic system of non-linear equations takes too long
I am trying to solve a set of system of symbolic non-linear equations:
...
4
votes
1answer
61 views
Nonlinearmodelfit with integral or nintegral as constrain
Until now I have been using the Nonlinearmodelfit without any issues, but I want to add a new constrain (Integral or NIntegral) to my modelfit.
My fitting function is ...
0
votes
1answer
101 views
Global optimisation - Error bound on NMaximize?
Is it possible to obtain an error bound on NMaximize? e.g. convert the number returned by NMaximize into a rigorous upper bound ...
1
vote
0answers
43 views
Tackling variational problem with constraints [closed]
I need to minimize (preferably symbolically) functional with constraints:
$$
F = \int_{0}^{\pi/2} f(x)cos{x}dx\,\\
1.1 \geq f(x) \geq 0\\
2.\int_{0}^{\pi/2} f(x)dx=Const\\
3. f(0) =1\\
4.f(\pi/2) = 0\...
0
votes
1answer
53 views
1
vote
1answer
104 views
Constrained NDSolve
Consider n particles constrained on the surface of a unit sphere. $i^{th}$ particle experiences a force from every other $j^{th}$ of the form $$\vec{f_{ij}}=\frac{k ...
5
votes
1answer
139 views
How do I tell FindMinimum to only work with positive, real numbers?
I have a function that I'm trying to minimize. It currently works reasonably well with this:
...
0
votes
0answers
40 views
Maximising the minimum of a linear combination of polynomials
I have list of finArray of 6 rational polynomials, of degrees of about 4 to 6, in around 200 variables allVars, along with a ...
0
votes
2answers
95 views
Is it possible to use Reduce in a way that "eliminates" some unwanted variables, and only gives constraints between wanted variables?
Reduce[{x == z, y == z}] gives y == z && x == z but say I'm only interested in constraints that appear between ...
0
votes
1answer
41 views
Find parameter value for which sharply-peaked constrained 3d-integral equals 1
I want to find the value (desirably to high-precision) of the parameter $i$ for which
the constrained 3d integration
...
0
votes
0answers
39 views
What happens when NMinimize constraints are unsolvable
I have an algebraic function in many variables which outputs a vector $v$.
The coefficients of the vector are high degree polynomials in many variables.
I want to maximize $\;v[[1]] /Norm[v]\;$ ...
1
vote
1answer
83 views
Finding whether the convex cone from a vector list is null
Given a list of vectors, I want to find whether there exists a vector such that its dot product with those in the list is all (semi)positive, or at least above a certain small negative value.
5
votes
3answers
231 views
How to randomly generate a positive semidefinite matrix?
How would I randomly generate a positive semidefinite matrix? I'm aware how to generate a random $n\times n$ matrix with real values between -1 and 1 with
...
1
vote
1answer
46 views
Show, if possible, small isolated "islands" in the unit cube using RegionPlot3D
I have a certain three-dimensional constraint
...
1
vote
1answer
168 views
ArgMin over intervals and discrete sets
I was playing with ArgMin but I'm not sure how to use it for constrained optimization.
For example,
ArgMin[x^2, x]
returns <...
1
vote
2answers
54 views
Find maximum of x given a bunch of constraints [closed]
Trying to find maximum of x given that '''0<=x<=3''' and some other stuff. This works fine:
Clear[x, y]
FindMaximum[{x, 0<=x<=3}, x]
But this does ...
3
votes
3answers
211 views
Constraint of NDSolve with an integral of the solution
I'd like to use NDSolve and to make a constraint with an integral.
For example, take the very simple : $$f'(x)=-f(x)/x_0 $$
the solution is $$f(x)=f_0 e^{-x/x_0} $$
And $f_0$ is given by : $$\int_0^{+\...
1
vote
2answers
110 views
Optimize with constraints
I want to find the smallest $k$ such that $kx^2 \ge (\sin(x)-x)^2$ for all scalar $x\in[a,\ b]$? Obviously, I can do it analytically, but how can I do it (symbolically) in Mathematica? I am new to ...
0
votes
1answer
193 views
0
votes
1answer
67 views
NonlinearModelFit failing because varible range [closed]
I'm trying to fit a specific equation to a plot of points but its failing because the equation has a square root in it and I need to keep the values of x between a certain range. I know how to do this ...
4
votes
3answers
529 views
How to set a tolerance level for equality constraints
Given two equality constraints: x+y==250 and z+p==65 where x=190, y=50, z=45, p=15, I want ...
