Questions tagged [findinstance]
The findinstance tag has no usage guidance.
1
vote
2answers
26 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
83 views
FindInstance and cosine system of equations
I'm intrigued by Mathematica indisposition to find an example of the following system of equations
$$
\cos(x) + \cos(y) + \cos(z) = \lambda_1,
$$
$$
\cos(x+u) + \...
6
votes
1answer
78 views
What are the 'special or interesting points in the set' returned by FindInstance?
The documentation for FindInstance[] says:
The instances returned by FindInstance typically correspond to special or ...
0
votes
0answers
41 views
Why is FindInstance unable to find multiple pythagorean triples?
If I input the code
FindInstance[x^2 + y^2 == z^2 && 0 < x && 0 < y && 0 < z, {x, y, z}, Integers, 2]
Mathematica outputs
"...
1
vote
1answer
51 views
Reducing system of 10 inequalities
I have the following system of inequalities of real variables
...
3
votes
2answers
99 views
Improving FindInstance efficiency
I am relatively new to Mathematica and my function has been running for over a month now. I am beginning to think I may never get a solution or that there is a mistake in the code, which means a ...
2
votes
2answers
116 views
On the solvability of the Diophantine equation $a(x^2-y^2)+2bxy=1$
Take two integers $a,b$ with $\mathrm{GCD}(a,b)=1$ and $a$ odd. Consider the Diophantine equation
$$
a(x^2-y^2)+2bxy=1,\qquad x,y\in\mathbb Z
$$
Is there any efficient way to determine whether such ...
0
votes
1answer
55 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
72 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
101 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
284 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....
1
vote
0answers
215 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
54 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
259 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
105 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
134 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
101 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
106 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 ...
