Questions tagged [findinstance]
The findinstance tag has no usage guidance.
27
questions
1
vote
0answers
49 views
What should I do to find an instance that meets the requirements [closed]
In a non-obtuse triangle $\triangle ABC$, the sides of the triangle satisfy the following conditions $a^2 > bc$ , $b^2 > ac$ and $c^2 > ab$. Now we need to verify whether the inequality $$(a +...
1
vote
1answer
52 views
0
votes
2answers
38 views
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 ...
0
votes
0answers
49 views
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
...
0
votes
0answers
49 views
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 ...
3
votes
1answer
102 views
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 ...
1
vote
1answer
40 views
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 ...
0
votes
1answer
52 views
1
vote
0answers
47 views
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.
...
1
vote
2answers
42 views
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,
...
3
votes
1answer
86 views
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) + \...
6
votes
1answer
85 views
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 ...
0
votes
0answers
60 views
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
"...
1
vote
1answer
75 views
Reducing system of 10 inequalities
I have the following system of inequalities of real variables
...
3
votes
2answers
124 views
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 ...
2
votes
2answers
125 views
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 ...
asked Nov 14 '18 at 17:45
AccidentalFourierTransform
8,8341 gold badge14 silver badges48 bronze badges
0
votes
1answer
185 views
FindInstance with a symbolic constant
Please consider
FindInstance[m >= 0 && x >= 0 && x <= m, {x}]
for which, I would like a parametric answer ...
2
votes
1answer
90 views
FindInstance within a range
I am trying to find particular solutions to my inequality for two positive integers $a$ and $b$:
FindInstance[a<f[etc...]*b,{a,b},Integers]
However I want $a$ ...
1
vote
3answers
115 views
Checking Rationality Using FindInstance
I need to find example if $x,\sqrt{x^2+6},\sqrt{x^2+12}$ all can be rational at once or not. But the following command
...
3
votes
4answers
336 views
Problems with FindInstance in v. 11
I have been trying to solve a system of linear equations and linear inequalities with 18 unknowns. I would think that for Mathematica giving an answer to such question will be a matter of milliseconds....
3
votes
0answers
396 views
solving linear systems with parameters
I am trying to solve simple, small linear systems, with parameters. I would like to have the result shown for various values of the parameter. RowReduce[],
...
1
vote
0answers
71 views
What is the algorithm used in FindInstance? [closed]
Is FindInstance guaranteed to find an instance if one exists? Conversely, if it does not find an instance, does that mean an instance does not exist at all? Finally, is there a way to change the ...
6
votes
5answers
310 views
Faster way to pick pairs of integer coordinates from a “region”
I am trying to find a faster way to do this than what I have put together or by looping through a bunch of points.
I want to select all pairs of integer points ((x1,y1),(x2,y2)) such that:
Point (x1,...
0
votes
1answer
118 views
Get a feasible solution
Link : Reduce time taken to get feasible solution
I have 18 inequations with 4 variables vars2 = {arb[1], arb[2], arb[3], arb[4]} , To get a feasible solution, NMinimize and Nmaximize were used as ...
1
vote
0answers
160 views
Error using NMinimize/NMaximize : The initial region specified may not contain any feasible points
Link : Reduce time taken to get feasible solution
An example of 18 non linear inequations with 4 variables is given in the image. But I have a set of 32 non linear inequations with 9 variables (I ...
3
votes
0answers
126 views
(FindInstance) Speeding up a slow integer program by converting to a boolean program
Here is an integer program with a bunch of inequality and equality constraints. FindInstance takes 2 seconds to solve it.
...
7
votes
0answers
139 views
FindInstance boolean program is slow, but fast with BooleanConvert
FindInstance can be incredibly slow to solve a boolean program, but it can be significantly improved by using BooleanConvert to ...
