Linear Equation in SAP

Hi Gurus,
I got a requirement to develop Simulator Process in which we are using Linear Equation for solving.
Linear Equation is wat we studied in School days...
3x + 2y + 7z = 20. (meaning: 20 is my target.. i want to know how much of x, y, z is added to achieve my target)
5x + 6y + 6z = 50.
6x + 2y + 2z = 10.
i want to know the values of x, y, z(this variable will be up to 10 also).
I know to solve manually.
Can you tell me is ther any function module to acheive this...
Or any easy way to develop in SAP?????
Thanks n Regards
Aravindh Mani

Hi,
I dont think there is a standard FM for this. You can better try to code the logic manually for this.
Regards,
Vik

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Is there a limit on the size of the input for the Solve Linear Equations block?

Hello,
I'm trying to figure out why the Solve Linear Equations block will properly function with some sets of data and why it won't with others. What my program is doing is taking a signal and comparing it with a batch of sine and cosine waves to try and pick out patterns in the data. I have different sample sizes and it seems to work when I throw 3900 points at it. However, I have another set with 4550 points and it gives me incorrect amplitudes for my sinusoids. Is there some limit to the size of the matrices that I can give this block? Or is there some other workaround that still allows me to keep all of my data?
Thanks,
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Well, the best way to show what I expect is to see the entire program. It's pretty evident that when looking at the graphs, something isn't right. What is supposed to happen is that the runout amplitudes are found, and then those sinusoids are subtracted from the initial data, leaving tooth to tooth data and noise. When I use the larger arrays, it seems as though not all of the data gets through (count the peaks on the product gear runout graph vs. initial) and the amplitudes are much to small, such that nothing is really taken out and the tooth to tooth data looks like the initial data.
Also, we will also be using an FFT, but it will be limited to only determining the frequencies we should check. I've fought with the fft blocks quite a bit and I just prefer to not use them. Plus, the guy I'm writing this for wants exact answers and does not want to pad or resample the data or use windows.
The exact number of data points isn't important (ie. 4550 vs 4551) since I use the array size block to index the for loop.
As for typical values, they can change a lot based on materials. But, the original 3900 data point sets and the 4550 data point sets used practically identical gears. So, use the original 3900 sets I've included as references (check the RO array block numbers to compare).
I've included 3 3900 samples, 3 4550 samples, and 3 4550 samples that have been truncated to 3900 or so as constants on the block diagram.
Also, the check for additional runouts (like 3 per rev, 4 per rev, etc..) is optional, but if you choose to use it, use positive integers only.
I don't know how much of this program will make sense and I have wires running everywhere.. so good luck. Keep in mind I'm only a student and I hadn't touched Labview until about 2 or 3 months ago.
Thanks,
David Joseph
Attachments:
Full example.vi ‏139 KB

Is there a linear equations VI thatI can use for inputting the coefficients with variables attached to them? Thank you.

Is there a linear equation VI that I can use for inputting the coefficients with variables attached to them? I am currently studying elec engineering and am in the thick of transient analysis. It is very time consuming figuring the mesh and nodal analysis in the transform domain. With 3 branches in a mesh analysis the resistors, inductors and capacitors are represented with variable s in them. I need to determine in the transform domain then convert to the time domain. One equation goes like this: (3+2s+1/4s)i1s - (2s)i2s - (1/4s)i3s = 6/s -6. The other equations are similar. I must keep the variable s in the equation and solve it with s in the result. I made several VIs for determining simultaneous linear equations some for complex numbers and they work great. This one has me a little stumped. I thinking that maybe Labview doesn't have a VI for this. The other VIs were fine because you just plugged in the numbers and ran the VI and got your result. Any VIs that do LaPlace transform operations?
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Hello Tom,
You can find a VI for doing Laplace transforms in Functions->Analyze->Signal Processing->Frequency Domain (this VI is only available in the Full and Professional versions).
You may also find the following tutorial of help in working with linear systems in LabVIEW.
Linear Systems in LabVIEW
Keep up to date on the latest PXI news at twitter.com/pxi

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I'm trying to solve some ill-conditioned simultaneous linear equations for a graphics application. Gaussian elimination using total pivoting on doubles isn't accurate enough. Does anyone know any better techniques?

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I've implemented a modified Linear Levenberg Marquardt function for gauss fitting of spectral data, but have problems from time to time where I simply can't fit a specific data set.
I've traced the problem to the function "Solve Linear Equations" outputting NaN for one or more solution vectors (Not all) which then plays havok with my function.
I've located a data set which is initially OK, but which after solving the linear equations has NaN as the second element of the solution vector array. Changing the matrix type to something other than "generic" gets rid of the NaN for this particular data set, but gives problems with others which work with the "generic" matrix type.
Since my mathematics lectures in college are a few years away now, I'm asking someone out there if they can help me with my problem. I can supply a "corrupting" data set if this would help, or maybe someone knows this problem and has a work-around?
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Using LV 6.1 and 8.2.1 on W2k (SP4) and WXP (SP2)

Hi Altenbach,
The data can have a significant amount of overlap. Typically three to four groups of peaks fully resolved, but each group can have up to 4-5 peaks in them, partially visible only as shoulders.
The start value "problem" is more or less solved (but as usual, not yet finished).
I've got an approximate first-guess peak find running which does a pretty good job of finding the peaks I need, and I then fit the height and FWHM first before doing a full optimisation (The Sub-VI approach allows much more flexible fitting models).
The fitting works well on almost all data sets. There are simply some spectra which (although visibly hardly different to others which work perfectly) do not fit, i.e. generate the NaN response from the "solve linear equations" function. It's a numeric problem (bug?), I'm sure, and not strictly a peak location or resolution problem. then again, I may be wrong.
I refer to the standard "LevMar" VI as being linear, because it assumes a linear relationship between the variable variation and the end mse used for optimisation. This is where the "Solve linear Equations" comes in. Since the relationship is almost certainly not linear (foe example when peaks overlap), I thought maybe the non-linear coefficient guess may yield better results. I've had a quick look through the non-linear LEV-MAR function, but don't understand it yet ot the extent I understand the linear one. It does indeed seem to take a slightly different approach (once you look past the whole parsing code of the "linear" function.
I'll need some time to get some understanding of the non-linear code.
Attached are some example spectra (One which works, and one which doesn't).
Thanks again
Shane
Using LV 6.1 and 8.2.1 on W2k (SP4) and WXP (SP2)
Attachments:
Spectra.zip ‏3 KB

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I have the following equation that I need to solve a, b and c. y = a+bexp(-x/c). Is there a VI that is written to help me?

i don't understand what do you suppose to mean?
you have not a,b and c values and you wanna solve 3 unknown variables with just one equation?
do you think is that possible?
even you had x and y values!
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Attachments:
formula_node_example.vi ‏25 KB

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I'm not too proud to accept solutions as well. Many thanks.

Is it what you wanted ?
In cells of column B, the formula is :
=IFERROR(INDIRECT(ADDRESS(1,2,,,A&" "&$A$1)),"")
Between the late double quotes I insreted the character INFINITY ($221E)
Yvan KOENIG (VALLAURIS, France) mercredi 21 avril 2010 20:44:36

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Here is the problem:
I have 2 point A(x1,y1) & B(x2,y2) ,what i need is find a point C(x3,y3);
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Thanks.

Here is the problem:
I have 2 point A(x1,y1) & B(x2,y2) ,what i need is find a point C(x3,y3);
This point C should :
1)form a line AC that goes throught point B
2)C is intersectin point of the line AC & one of screen edges :
(left=0,right=ScreenWidht,top=0,bottom=ScreenHeight)
3) The C point form a line (vector?) A--->C & not C--->A
I need to fighure out the C ,so if A is a projectile source,the projectil
will fallow the Target (C point) from A---->C..
Hope that clear enought,i would realy appreciate if i get some help soling this math problem (im not good in math) , that will be great if i get some code ( routine that takes x1,y1,x2,y2 as parametres and calcule x3 and y3)
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THANKS!!!!
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kind regards

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Dear all,
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Regards

Hi,
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Linear Equation in SAP

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