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Questions tagged [findinstance]

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1
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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
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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
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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 ...
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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
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1answer
51 views

Reducing system of 10 inequalities

I have the following system of inequalities of real variables ...
3
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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 ...