Questions tagged [findinstance]
The findinstance tag has no usage guidance.
61
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Finding only non-negative roots with FindRoot
Given an arbitrary function F, how do I force FindRoot to look only for non-negative roots, returning nothing otherwise?
- 4,362
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42
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Finding the similarity transformation between two symbol matrices
I have two symbol matrices mA and mB, which are similar matrices.
...
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60
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Can I use FindInstance to prove an algebraic identity?
This question arose from a [now removed] MathOverflow discussion, where a Null result from a FindInstance query was used to prove that $f(x_1,x_2,\ldots x_n)\neq 0$ has no solution in $\mathbb{R}$. My ...
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Calculating eigenvalues and solving inequalities with parameters
I would like to calculate b in terms of c and a, in order to satisfy the following conditions:
...
- 11
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44
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An error occurred while using FindInstance to find a matrix that meets the constraint conditions
I want to use MMA to prove an exercise in textbook: mA is a n-level square matrix.
Proof: mA.mA==mA is true if and only if ...
- 1,719
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107
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Mathematica generating 'incorrect' Cuboids
Mathematica 13.1 for some reason gives an error for the following code:
...
- 203
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75
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Finding a (sufficient) condition for an inequality - Solve takes too long
I have the following inequality
$ 2 \sqrt{2} n^2 \sqrt{\frac{r}{r-1}} \exp \left(2^{-\frac{\sqrt[3]{\log (n)}}{10 \sqrt[3]{\log (r)}}} \left(\frac{1}{r+1}\right)^{-\frac{\sqrt[3]{\log
(n)}}{10 \...
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804
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Solving a Simple 'Sum and Product' Problem
I am trying to solve a simple 'sum and product' problem. Basically, the sum of four prices and the product of those four prices are numerically equal (you must, of course, disregard the units). The ...
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122
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126
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FunctionDomain and FindInstance problem
I have some functions including many real parameters as follows:
For example,
...
- 355
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How to find rational roots of a polynomial in 5 variables in a cube
I am trying to find rational numbers $m,k,l,o,z,R$ such that
R^12 - (k l^2 m - l m^2 o - k^2 l z + l o z) R^6 + o^3*z^3 == 0
in the following cube:
...
- 647
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How can I solve this system of 6 simple quadratic diophantine equations in four variables?
I generated this text file containing tuples $(\sqrt{s}, \sqrt{t}, \sqrt{u}, s,t,u,t+u,t+u-s,t-s)$ where the six variables $s,t,u,t+u,t+u-s,t-s$ are all squares. An excerpt of the data set is:
...
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Challenges and Opportunities of `FindInstance` Command
I'm testing the FindInstance capabilities and ran into one problem that behaves similarly with different types of inequalities. I calculate two points satisfying ...
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FindInstance specifying reals increases the time significantly and gives errors
I was wondering if there is any way to put time constraint on FindInstance.
My problem is as follows: I want to find two, $2 \times 2$ matricies $A,B$ given $Tr(A)$, $Tr(B)$, $TR(AB)$, $Det(A)$ and $...
- 647
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Tips to help FindInstance with a lot of complicated inequalities
I'm trying to find a numerical instance (I don't need arbitrarily high precision) of solution to 7 relatively complicated inequalities (plus the region specification) involving 8 variables.
The ...
- 383
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84
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Defining new Domain for variables
I am trying to define a new Domain for variables to use with functions like FindInstance or Solve. For example, If I wanted to solve x+y+z=1 over the Reals, I'd get a large solution space. But If I ...
- 181
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How to calculate multiple solutions from big to small with FindInstance funtion
I want to find the nearest 50(or 80, even 100)solutions under 1.4628 from big to small, I tried FindInstance function in MMA, but still cannot get the desired results I need.Here is my code:
...
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Finding all solutions to coupled algebraic equations without exhaustive enumeration
A Cambridge University mathematics interview question states:
Find all $a,b,c,d,e,f \in \mathbb{N}$ such that
$$a + b + c = d \cdot e \cdot f$$
and
$$d + e + f = a \cdot b \cdot c$$
(There are a ...
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Elementary number theory problem and FindInstance
Find $\{ m,n \} \in \mathbb{Z}$ such that $m \neq n$ and $m^n = n^m$.
This has (unordered) solutions $\{ 2, 4 \}$ and $\{ -2, -4 \}$, as can be easily checked.
I'm of course hoping for an analytic ...
- 38.2k
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167
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Solve equation with summation and factorial over Integers
Find all $\{ m, n \} \in \mathbb{Z}^+$ such that
$$\sum\limits_{k=1}^m k! = n^2 .$$
The two solutions are $\{ m,n \} = \{ 1,1 \}$ and $\{ 3,3 \}$, as can be confirmed. Here is how to solve this ...
- 38.2k
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Find smallest instance satisfying certain inequalities
I need a "clean" way to find the smallest solution to some (in)equalities given by Reduce and containing only one variable ...
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88
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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 ...
- 113
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56
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Restrict FindInstance to exact value
I would like to restrict the FindInstance function to exact values (ex. 2Pi/3)
The following doesn't work
...
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Why does `FindInstance` refuse to find a second instance, in a number theory problem?
Hi I am looking for reversible Markov generating matrices of order three, whose upper (2,2) block has integer eigenvalues. There are 5 free parameters; I specified 2
...
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94
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Does FindInstance traverse the entire domain?
If the result of FindInstance[expr<=0,vars,dom] is empty set, can it mean that expr is always greater than ...
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84
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How to show all global minimizers?
This is a follow-up to this question and I'm aware of this question for the local minimizers case.
Consider, for $0\leq \epsilon\leq 1$ and $0<q,p<1$, the function
$$
\begin{align}
f(\...
- 4,362
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117
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Finding multiple minimizers
Is it possible to find all (or as many as possible) minimizers of a given function? For example, minimizing the function $\cos(\pi(p-q))+\cos(\pi(q+p))$ for $-3\leq p,q\leq 3 $ can be done using ...
- 4,362
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289
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FindInstance won't compute this simple expression
I want to find instances where this standard 3x3 symmetric matrix has only positive eigenvalues.
So I run ...
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1
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41
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Find a non-convex instance for a non-convex set function with FindInstance
Let $f$ be a non-convex set function defined on a set $L$.
Hence there are subsets $A,B\subseteq L$ such that
$$f(A)+f(B)>f(A\cup B)+f(A\cap B).$$
I tried to use FindInstance function to find a non-...
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Obtain fairly sampled data set subject to a condition?
I need to obtain a random distribution of some parameters {t1,t2,t3} subject to a set of conditions. For example,
...
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121
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FindInstance taking too long
I just started to use Wolfram Alpha Notebook Edition. I am using FindInstance command to evaluate the sign of an expression with $8$ variables, under simple constraints, but it takes too much time. Do ...
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My Program using NSolve and FindInstance has been running for days without a solution
I have a system of 5 non-linear equations and 5 unknowns (p1,p2,p3,p4,p5 bellow), and a few inequalities. I am trying to understand whether the solution is unique.
For this purpose, I tried to run ...
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System of 15 equations in 23 variables
$$
1-k_0^2=0, \frac{1}{2} \left(-7 \alpha ^2+38 \alpha +2 c_3 (\alpha +\beta-3)+2 c_6-2 k_1^2-2 k_5^2-48\right)=0, c_5-k_2^2-k_{10}^2=0, c_8(\alpha +\beta -5)+5 c_{10}-k_3^2-k_6^2-k_8^2-k_{11}^2-2 k_2 ...
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Solve inequalities
I use FindInstance to find a set of real parameters to satisfy the following inequality
$-3 c_{11}-k_4^2-k_7^2-k_9^2>0$,
$$
-4 \alpha^6+84 \alpha^5-721 \alpha^4+3228 \alpha^3-7924 \alpha^2+10080 \...
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How can I find some values for which an expression is real?
I've a complicated expression which depends on several variables. I want to find some values for those variables such that the complicated expression is real. How can I do that?
The obvious command ...
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64
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Turning FindInstance into True or False
I have a function where I input a certain vector of parameters and it gives me the output of 16 FindInstances. So, a typical output will look something like this
...
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Finding a solution to a modular problem efficiently
I want to find a naïve hash function of the form Mod[a x + b, 2^p] which would produce a value less or equal to v for all ...
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Why does FindInstance take so long: It is faster with more restrictions than with less?
A support case with the identification [CASE:4347836] was created.
I just noted this little puzzle on twitter by Brillant.org:
\begin{align} A B C\\+ BCA\\ = CDE \end{align}
Given that $A$ is even ...
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FindInstance confused by CoprimeQ
For some reason when I type
FindInstance[a + b == c && CoprimeQ[a, b, c] == True, {a, b, c}, Integers]
Mathematica just immediately returns my input as ...
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109
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FindInstance Returns "Aborted" [closed]
Edit: Apologies, the question needs to be reworked, because I cannot reproduce the original problem using this code.
I don't delete the question, in case someone is preparing an answer at the moment.
...
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How to use a given list of values for a parameter in FindInstance?
How should I specify a discrete range for a parameter as one of the conditions in FindInstance? MemberQ/Element functions don't seem to work.
For example,
...
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FindInstance and cosine system of equations
I'm intrigued by Mathematica indisposition to find an example of the following system of equations
$$
\cos(x) + \cos(y) + \cos(z) = \lambda_1,
$$
$$
\cos(x+u) + \...
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What are the 'special or interesting points in the set' returned by FindInstance?
The documentation for FindInstance[] says:
The instances returned by FindInstance typically correspond to special or ...
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86
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Why is FindInstance unable to find multiple pythagorean triples?
If I input the code
FindInstance[x^2 + y^2 == z^2 && 0 < x && 0 < y && 0 < z, {x, y, z}, Integers, 2]
Mathematica outputs
"...
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Reducing system of 10 inequalities
I have the following system of inequalities of real variables
...
- 1,598
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192
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Improving FindInstance efficiency
I am relatively new to Mathematica and my function has been running for over a month now. I am beginning to think I may never get a solution or that there is a mistake in the code, which means a ...
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On the solvability of the Diophantine equation $a(x^2-y^2)+2bxy=1$
Take two integers $a,b$ with $\mathrm{GCD}(a,b)=1$ and $a$ odd. Consider the Diophantine equation
$$
a(x^2-y^2)+2bxy=1,\qquad x,y\in\mathbb Z
$$
Is there any efficient way to determine whether such ...
