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MITHOOON

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06-08-2016 04:48 AM

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I have the following system of equations:

90x1+85x2+55x3+52x4=900;

2.5x1+4.5x2+35x3+34x4=800;

Since the number of unknowns are more than the number of equations, the system is underdetermined. So it has infinite number of solutions. But I need only the positive solutions. That is, the valuse of the unknwns should be greater than zero. Is there any way to find the solution in labview?

Norbert_B

Proven Zealot

06-08-2016 07:07 AM

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@MITHOOON wrote:

[...] Is there any way to find the solution in labview?

Sure there is.... if you write a program which does this. LV is a programming language, not a mathematical script solver.

Before going into implementation, you have to know how you want to achieve a result.

For example: You could implement a program which plots the result of the first equation, left part, depending on X. You could mark all instances in the graph where the value equals 900.

Repeat this for the second equation. Any X which is a valid solution for first AND second plot is a result you are looking for.

There are, however, better methods. Most of them are listed in technical literature.....

Norbert

Norbert

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CEO: What exactly is stopping us from doing this?

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CEO: What exactly is stopping us from doing this?

Expert: Geometry

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Alexander_Sobolev

Active Participant

06-08-2016 09:59 AM - edited 06-08-2016 10:02 AM

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What do you call a solution?

4D matrix with marked surface? = list of (x1, x2, x3, x4) values on some grid.

Analytical description of the surface (expressions of the lines limiting 2D flat surface in 4D space)?

Program that gives you x1 and x2 if you set other variables?

Norbert_B

Proven Zealot

06-08-2016 10:27 AM

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@Alexander_Sobolev wrote:

What do you call a solution?

4D matrix with marked surface? = list of (x1, x2, x3, x4) values on some grid.

Analytical description of the surface (expressions of the lines limiting 2D flat surface in 4D space)?

Program that gives you x1 and x2 if you set other variables?

I **assume** that this should not be x1, x2, x3,... but x^1, x^2, x^3, ...

OP: Could you clarify?

Norbert

Norbert

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CEO: What exactly is stopping us from doing this?

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Bob_Schor

Knight of NI

06-08-2016 12:15 PM - edited 06-08-2016 12:16 PM

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@Norbert_B wrote:I

assumethat this should not be x1, x2, x3,... but x^1, x^2, x^3, ...OP: Could you clarify?

Norbert

Norbert,

I think x1 is x-sub-1, not x-to-the-first-power. It looks like he's trying to solve a system of linear equations, where there are fewer equations than unknowns (4 unknowns, x1, x2, x3, x4 a.k.a. x, y, z, and w).

BS

06-10-2016 01:48 AM

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Hii Nobert,

How to plot an equation with 4 unknowns?!!! 4D plot?

Norbert_B

Proven Zealot

06-10-2016 02:37 AM

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If Bob is correct, the proposal with the graph is of course quite difficult.

However, the question is more a generic computer science question (building an algorithm or find suitable existing methods) rather a LV question.

Norbert

Norbert

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CEO: What exactly is stopping us from doing this?

Expert: Geometry

Marketing Manager: Just ignore it.

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CEO: What exactly is stopping us from doing this?

Expert: Geometry

Marketing Manager: Just ignore it.