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Thread Subject:
how to solve this higher polynomial function?

Subject: how to solve this higher polynomial function?

From: bo

Date: 3 Mar, 2010 11:10:21

Message: 1 of 17

Linear model Poly8:
       fittedmodel1(x) = p1*x^8 + p2*x^7 + p3*x^6 + p4*x^5 +
                    p5*x^4 + p6*x^3 + p7*x^2 + p8*x + p9
     Coefficients (with 95% confidence bounds):
       p1 = -8.739e-010 (-4.795e-008, 4.62e-008)
       p2 = -1.338e-008 (-1.811e-006, 1.784e-006)
       p3 = 7.195e-007 (-2.983e-005, 3.127e-005)
       p4 = 8.171e-006 (-0.001298, 0.001315)
       p5 = -0.0003242 (-0.01082, 0.01017)
       p6 = -0.002373 (-0.2801, 0.2753)
       p7 = -0.02718 (-1.754, 1.699)
       p8 = -0.3535 (-17.13, 16.42)
       p9 = 305.7 (239.8, 371.6)

Anyone can help me to solve this higher polynomial function ? Then compare the result?Thanks a lot

Subject: how to solve this higher polynomial function?

From: John D'Errico

Date: 3 Mar, 2010 12:06:05

Message: 2 of 17

"bo " <bobpong1979@hotmail.com> wrote in message <hmlg2s$k88$1@fred.mathworks.com>...
> Linear model Poly8:
> fittedmodel1(x) = p1*x^8 + p2*x^7 + p3*x^6 + p4*x^5 +
> p5*x^4 + p6*x^3 + p7*x^2 + p8*x + p9
> Coefficients (with 95% confidence bounds):
> p1 = -8.739e-010 (-4.795e-008, 4.62e-008)
> p2 = -1.338e-008 (-1.811e-006, 1.784e-006)
> p3 = 7.195e-007 (-2.983e-005, 3.127e-005)
> p4 = 8.171e-006 (-0.001298, 0.001315)
> p5 = -0.0003242 (-0.01082, 0.01017)
> p6 = -0.002373 (-0.2801, 0.2753)
> p7 = -0.02718 (-1.754, 1.699)
> p8 = -0.3535 (-17.13, 16.42)
> p9 = 305.7 (239.8, 371.6)
>
> Anyone can help me to solve this higher polynomial function ? Then compare the result?Thanks a lot

Sigh.

This is an example of using a computer without ever
actually thinking about what you are doing. Just
throw the numbers at a computer, and let it think
for you.

By "solve" here, I assume that you intend to solve for
the roots of the equation

    fittedmodel(x) == 0

and you wish to bring your uncertainty in the
coefficients of this model into the process. Thus,
if p1 through p9 are normally distributed, with
95% bounds as given, what might the distribution
of the roots be? (I cannot see any other meaning
for the word solve, but even if that is not your
intended meaning, many of my comments below
will still be meaningful.)

The first (and major) problem is in those bounds.
LOOK AT YOUR RESULTS. Do not just push numbers
through a computer without thinking. As soon as you
stop thinking, you begin to get computer generated
trash. Garbage in, garbage out.

Pick on of those coefficients arbitrarily to look at.

   p8 = -0.3535 (-17.13, 16.42)

So this apparently means that the estimated value of
p8 is -0.3535, but with 95% bounds of -17.13 to
+16.42!!!!!!!!!! Do you see that this means p8 may
be essentially ANY number in that range? As such,
it is indistinguishable from zero.

This term should be dropped from your polynomial
model. Were you to learn about regression modeling,
such a course would tell you to drop coefficients with
such large bounds that contain zero from your model.
Start with the highest order terms first of course, then
keep reducing the order of the model until the terms
become statistically different from zero.

The point in all of this, is you should NEVER fit such
a high order polynomial model to data without thinking
about what you are doing. The regression model that
you have generated here is pure, unmitigated garbage.
It is meaningless crapola. The polynomial that you have
is useless. You are over-fitting the problem, with too
high order of a model to achieve meaningful predictions
of any sort.

Next, you forget (or maybe don't actually know) that
those bounds on your coefficients are not independent
bounds. In fact, the coefficients actually have a complete
covariance matrix. So when these bounds are so large,
the covariances will also be huge, and very significant in
any procedure that you later apply.

I should point out that in terms of polynomial modeling,
more is not always better. If a low order fit is nice, but
not good enough, don't just make the order higher and
expect to trust what you get. Just because you can force
the computer to generate arbitrarily high order models
means nothing.

Whenever you use a computer to analyze your data, think
about the results that you get, at every step. Make sure
that you understand the tools you use to do the analysis,
and that you understand the output of those tools. Stop
at every step and plot everything. Look at what you get
to ensure that it is meaningful. Otherwise, expect garbage
like this.

John

Subject: how to solve this higher polynomial function?

From: Walter Roberson

Date: 3 Mar, 2010 17:12:45

Message: 3 of 17

bo wrote:
> Linear model Poly8:
> fittedmodel1(x) = p1*x^8 + p2*x^7 + p3*x^6 + p4*x^5 +
> p5*x^4 + p6*x^3 + p7*x^2 + p8*x + p9
> Coefficients (with 95% confidence bounds):
> p1 = -8.739e-010 (-4.795e-008, 4.62e-008)
> p2 = -1.338e-008 (-1.811e-006, 1.784e-006)
> p3 = 7.195e-007 (-2.983e-005, 3.127e-005)
> p4 = 8.171e-006 (-0.001298, 0.001315)
> p5 = -0.0003242 (-0.01082, 0.01017)
> p6 = -0.002373 (-0.2801, 0.2753)
> p7 = -0.02718 (-1.754, 1.699)
> p8 = -0.3535 (-17.13, 16.42)
> p9 = 305.7 (239.8, 371.6)
>
> Anyone can help me to solve this higher polynomial function ? Then
> compare the result?Thanks a lot

[27.99708697, 21.78654449+16.78673556*I, -1.715081315+23.37905185*I,
-25.56879926+16.62652042*I, -32.31309110, -25.56879926-16.62652042*I,
-1.715081315-23.37905185*I, 21.78654449-16.78673556*I]

The two real roots fit to within 10^(-6)

Subject: how to solve this higher polynomial function?

From: bo

Date: 4 Mar, 2010 15:30:23

Message: 4 of 17

"John D'Errico" <woodchips@rochester.rr.com> wrote in message <hmljbd$jjt$1@fred.mathworks.com>...
> "bo " <bobpong1979@hotmail.com> wrote in message <hmlg2s$k88$1@fred.mathworks.com>...
> > Linear model Poly8:
> > fittedmodel1(x) = p1*x^8 + p2*x^7 + p3*x^6 + p4*x^5 +
> > p5*x^4 + p6*x^3 + p7*x^2 + p8*x + p9
> > Coefficients (with 95% confidence bounds):
> > p1 = -8.739e-010 (-4.795e-008, 4.62e-008)
> > p2 = -1.338e-008 (-1.811e-006, 1.784e-006)
> > p3 = 7.195e-007 (-2.983e-005, 3.127e-005)
> > p4 = 8.171e-006 (-0.001298, 0.001315)
> > p5 = -0.0003242 (-0.01082, 0.01017)
> > p6 = -0.002373 (-0.2801, 0.2753)
> > p7 = -0.02718 (-1.754, 1.699)
> > p8 = -0.3535 (-17.13, 16.42)
> > p9 = 305.7 (239.8, 371.6)
> >
> > Anyone can help me to solve this higher polynomial function ? Then compare the result?Thanks a lot
>
> Sigh.
>
> This is an example of using a computer without ever
> actually thinking about what you are doing. Just
> throw the numbers at a computer, and let it think
> for you.
>
> By "solve" here, I assume that you intend to solve for
> the roots of the equation
>
> fittedmodel(x) == 0
>
> and you wish to bring your uncertainty in the
> coefficients of this model into the process. Thus,
> if p1 through p9 are normally distributed, with
> 95% bounds as given, what might the distribution
> of the roots be? (I cannot see any other meaning
> for the word solve, but even if that is not your
> intended meaning, many of my comments below
> will still be meaningful.)
>
> The first (and major) problem is in those bounds.
> LOOK AT YOUR RESULTS. Do not just push numbers
> through a computer without thinking. As soon as you
> stop thinking, you begin to get computer generated
> trash. Garbage in, garbage out.
>
> Pick on of those coefficients arbitrarily to look at.
>
> p8 = -0.3535 (-17.13, 16.42)
>
> So this apparently means that the estimated value of
> p8 is -0.3535, but with 95% bounds of -17.13 to
> +16.42!!!!!!!!!! Do you see that this means p8 may
> be essentially ANY number in that range? As such,
> it is indistinguishable from zero.
>
> This term should be dropped from your polynomial
> model. Were you to learn about regression modeling,
> such a course would tell you to drop coefficients with
> such large bounds that contain zero from your model.
> Start with the highest order terms first of course, then
> keep reducing the order of the model until the terms
> become statistically different from zero.
>
> The point in all of this, is you should NEVER fit such
> a high order polynomial model to data without thinking
> about what you are doing. The regression model that
> you have generated here is pure, unmitigated garbage.
> It is meaningless crapola. The polynomial that you have
> is useless. You are over-fitting the problem, with too
> high order of a model to achieve meaningful predictions
> of any sort.
>
> Next, you forget (or maybe don't actually know) that
> those bounds on your coefficients are not independent
> bounds. In fact, the coefficients actually have a complete
> covariance matrix. So when these bounds are so large,
> the covariances will also be huge, and very significant in
> any procedure that you later apply.
>
> I should point out that in terms of polynomial modeling,
> more is not always better. If a low order fit is nice, but
> not good enough, don't just make the order higher and
> expect to trust what you get. Just because you can force
> the computer to generate arbitrarily high order models
> means nothing.
>
> Whenever you use a computer to analyze your data, think
> about the results that you get, at every step. Make sure
> that you understand the tools you use to do the analysis,
> and that you understand the output of those tools. Stop
> at every step and plot everything. Look at what you get
> to ensure that it is meaningful. Otherwise, expect garbage
> like this.
>
> John

Thanks a lot John.But tell you I have only learnt matlab 2 weeks. Have not learnt how to walk but to run already.No choice it is my project.Anyway, thanks for your time and patience.

Subject: how to solve this higher polynomial function?

From: dpb

Date: 4 Mar, 2010 15:46:06

Message: 5 of 17

bo wrote:
> "John D'Errico" <woodchips@rochester.rr.com> wrote in message
> <hmljbd$jjt$1@fred.mathworks.com>...

...[a very nice commentary on regression modeling elided only for
brevity]...

> Thanks a lot John.But tell you I have only learnt matlab 2 weeks. Have
> not learnt how to walk but to run already.No choice it is my
> project.Anyway, thanks for your time and patience.


This is _NOT_ a Matlab issue John is addressing. It is the fundamentals
of the problem and the methodology itself. Unless and until you follow
the esteemed John D'E's advice and understand the bases and meaning of
regression modeling and what can (and probably even more importantly
canNOT) be inferred your project is doomed to failure.

Start w/ a tutorial on regression and/or other modeling techniques. If
you must, find the consulting statistics group in your university and
make use of them to at least get pointers to appropriate texts.

--

Subject: how to solve this higher polynomial function?

From: bo

Date: 4 Mar, 2010 16:02:06

Message: 6 of 17

dpb <none@non.net> wrote in message <hmokmh$ub9$1@news.eternal-september.org>...
> bo wrote:
> > "John D'Errico" <woodchips@rochester.rr.com> wrote in message
> > <hmljbd$jjt$1@fred.mathworks.com>...
>
> ...[a very nice commentary on regression modeling elided only for
> brevity]...
>
> > Thanks a lot John.But tell you I have only learnt matlab 2 weeks. Have
> > not learnt how to walk but to run already.No choice it is my
> > project.Anyway, thanks for your time and patience.
>
>
> This is _NOT_ a Matlab issue John is addressing. It is the fundamentals
> of the problem and the methodology itself. Unless and until you follow
> the esteemed John D'E's advice and understand the bases and meaning of
> regression modeling and what can (and probably even more importantly
> canNOT) be inferred your project is doomed to failure.
>
> Start w/ a tutorial on regression and/or other modeling techniques. If
> you must, find the consulting statistics group in your university and
> make use of them to at least get pointers to appropriate texts.
>
> --

Thanks both of you.It is my fault to address problem like this.I think I will study some tutorials regarding regression first before I really come to this problem.So sorry about that.

Subject: how to solve this higher polynomial function?

From: John D'Errico

Date: 4 Mar, 2010 16:45:19

Message: 7 of 17

"bo " <bobpong1979@hotmail.com> wrote in message <hmolhu$esr$1@fred.mathworks.com>...
> dpb <none@non.net> wrote in message <hmokmh$ub9$1@news.eternal-september.org>...
> > bo wrote:
> > > "John D'Errico" <woodchips@rochester.rr.com> wrote in message
> > > <hmljbd$jjt$1@fred.mathworks.com>...
> >
> > ...[a very nice commentary on regression modeling elided only for
> > brevity]...
> >
> > > Thanks a lot John.But tell you I have only learnt matlab 2 weeks. Have
> > > not learnt how to walk but to run already.No choice it is my
> > > project.Anyway, thanks for your time and patience.
> >
> >
> > This is _NOT_ a Matlab issue John is addressing. It is the fundamentals
> > of the problem and the methodology itself. Unless and until you follow
> > the esteemed John D'E's advice and understand the bases and meaning of
> > regression modeling and what can (and probably even more importantly
> > canNOT) be inferred your project is doomed to failure.
> >
> > Start w/ a tutorial on regression and/or other modeling techniques. If
> > you must, find the consulting statistics group in your university and
> > make use of them to at least get pointers to appropriate texts.
> >
> > --
>
> Thanks both of you.It is my fault to address problem like this.I think I will study some tutorials regarding regression first before I really come to this problem.So sorry about that.

As we have said, you need to use a lower order model
in this regression. There is a big tendency among novice
users of polynomial regression to decide that

1. The low order model looks nice, but is not accurate
enough.

2. Using a higher order model fits the data with lower
errors, therefore it must be better.

They invariably come to the conclusion that impossibly
high order models must be the best, the higher the order
the better, until MATLAB finally just gives up and refuses
to fit the model they have posed. The computer will do
whatever you tell it to do, with no complaints.

Use a lower order model, or recognize that your data is
insufficient to fit the model you have chosen. In this
event, you might choose to get better data.

John

Subject: how to solve this higher polynomial function?

From: bo

Date: 4 Mar, 2010 18:06:04

Message: 8 of 17

"John D'Errico" <woodchips@rochester.rr.com> wrote in message <hmoo2v$1oo$1@fred.mathworks.com>...
> "bo " <bobpong1979@hotmail.com> wrote in message <hmolhu$esr$1@fred.mathworks.com>...
> > dpb <none@non.net> wrote in message <hmokmh$ub9$1@news.eternal-september.org>...
> > > bo wrote:
> > > > "John D'Errico" <woodchips@rochester.rr.com> wrote in message
> > > > <hmljbd$jjt$1@fred.mathworks.com>...
> > >
> > > ...[a very nice commentary on regression modeling elided only for
> > > brevity]...
> > >
> > > > Thanks a lot John.But tell you I have only learnt matlab 2 weeks. Have
> > > > not learnt how to walk but to run already.No choice it is my
> > > > project.Anyway, thanks for your time and patience.
> > >
> > >
> > > This is _NOT_ a Matlab issue John is addressing. It is the fundamentals
> > > of the problem and the methodology itself. Unless and until you follow
> > > the esteemed John D'E's advice and understand the bases and meaning of
> > > regression modeling and what can (and probably even more importantly
> > > canNOT) be inferred your project is doomed to failure.
> > >
> > > Start w/ a tutorial on regression and/or other modeling techniques. If
> > > you must, find the consulting statistics group in your university and
> > > make use of them to at least get pointers to appropriate texts.
> > >
> > > --
> >
> > Thanks both of you.It is my fault to address problem like this.I think I will study some tutorials regarding regression first before I really come to this problem.So sorry about that.
>
> As we have said, you need to use a lower order model
> in this regression. There is a big tendency among novice
> users of polynomial regression to decide that
>
> 1. The low order model looks nice, but is not accurate
> enough.
>
> 2. Using a higher order model fits the data with lower
> errors, therefore it must be better.
>
> They invariably come to the conclusion that impossibly
> high order models must be the best, the higher the order
> the better, until MATLAB finally just gives up and refuses
> to fit the model they have posed. The computer will do
> whatever you tell it to do, with no complaints.
>
> Use a lower order model, or recognize that your data is
> insufficient to fit the model you have chosen. In this
> event, you might choose to get better data.
>
> John


Ok.Roger that.I will try to use a regression model to project or predict the trend curve passing through those data points .If more points are added in subsequently, this curve will also show the trend.Is it ok?

bo

Subject: how to solve this higher polynomial function?

From: dpb

Date: 4 Mar, 2010 18:31:57

Message: 9 of 17

bo wrote:
> "John D'Errico" <woodchips@rochester.rr.com> wrote in message
> <hmoo2v$1oo$1@fred.mathworks.com>...
...

>> Use a lower order model, or recognize that your data is
>> insufficient to fit the model you have chosen. In this
>> event, you might choose to get better data.
>>
...

> Ok.Roger that.I will try to use a regression model to project or predict
> the trend curve passing through those data points .If more points are
> added in subsequently, this curve will also show the trend.Is it ok?

Better, anyway... :)

Again, can't overemphasize the need to look at some underlying theory to
get a handle on what the statistics mean (and the assumptions made on
the data behind deriving them) in order to make reasonable judgments of
whether any of it makes any sense at all.

Certainly as John showed, at least looking at error bands on estimated
coefficients is a start.

For regression before ever even considering a model I can't over
emphasize the desirability of looking at plots of the data initially as
well as consideration of the location of the independent variables in
n-space, etc., etc., etc., ...

Again, this is the sort of think your advisor/prof/whoever should be
able to provide some guidance on before you get too far gone in just
data fitting.

--

Subject: how to solve this higher polynomial function?

From: bo

Date: 4 Mar, 2010 19:10:23

Message: 10 of 17

dpb <none@non.net> wrote in message <hmoudf$pd$1@news.eternal-september.org>...
> bo wrote:
> > "John D'Errico" <woodchips@rochester.rr.com> wrote in message
> > <hmoo2v$1oo$1@fred.mathworks.com>...
> ...
>
> >> Use a lower order model, or recognize that your data is
> >> insufficient to fit the model you have chosen. In this
> >> event, you might choose to get better data.
> >>
> ...
>
> > Ok.Roger that.I will try to use a regression model to project or predict
> > the trend curve passing through those data points .If more points are
> > added in subsequently, this curve will also show the trend.Is it ok?
>
> Better, anyway... :)
>
> Again, can't overemphasize the need to look at some underlying theory to
> get a handle on what the statistics mean (and the assumptions made on
> the data behind deriving them) in order to make reasonable judgments of
> whether any of it makes any sense at all.
>
> Certainly as John showed, at least looking at error bands on estimated
> coefficients is a start.
>
> For regression before ever even considering a model I can't over
> emphasize the desirability of looking at plots of the data initially as
> well as consideration of the location of the independent variables in
> n-space, etc., etc., etc., ...
>
> Again, this is the sort of think your advisor/prof/whoever should be
> able to provide some guidance on before you get too far gone in just
> data fitting.
>
> --

You are absolutely correct.Actually when I showed my advisor this uselss higher order polynomial function, as I am also a novice to matlab,my advisor should stop me at first place rather than asking me to solve it.So I just follow whatever my advisor said to do.That is why my direction totally went wrong. Is there any recommendation website of regression modeling? Thanks

Subject: how to solve this higher polynomial function?

From: dpb

Date: 4 Mar, 2010 19:58:20

Message: 11 of 17

bo wrote:
...

> You are absolutely correct.Actually when I showed my advisor this uselss
> higher order polynomial function, as I am also a novice to matlab,my
> advisor should stop me at first place rather than asking me to solve
> it.So I just follow whatever my advisor said to do.That is why my
> direction totally went wrong. Is there any recommendation website of
> regression modeling? Thanks

Unless he thought the exercise would lead to a recognition of a problem
that would be a learning experience I would have agree; if he was
serious in the recommendation one would hope it was simply a lack of due
consideration which would be disappointing at best but if is that
unfamiliar w/ the subject that would be a major failure it would seem...

Predating the web as a general place I can't say as where there is a
particularly useful site altho I'm sure there are probably several.

I've always been fond of Raymond H. Myers' book
_Response_Surface_Methodology_ as being relatively thorough but not
terribly advanced altho I'll admit much of that is from working w/ him
lo! so many years ago...

Another that is worthwhile is Box & Jenkins,
_Statistics_for_Experimenters_ for it's commonsense advice and
particularly a chapter or two on common pitfalls to avoid.

Both of these, of course, date me as the "old fogey" I have become; I'm
sure there are many much newer I've never seen that would be just as
suitable.

--

Subject: how to solve this higher polynomial function?

From: bo

Date: 4 Mar, 2010 22:37:21

Message: 12 of 17

dpb <none@non.net> wrote in message <hmp3ff$863$1@news.eternal-september.org>...
> bo wrote:
> ...
>
> > You are absolutely correct.Actually when I showed my advisor this uselss
> > higher order polynomial function, as I am also a novice to matlab,my
> > advisor should stop me at first place rather than asking me to solve
> > it.So I just follow whatever my advisor said to do.That is why my
> > direction totally went wrong. Is there any recommendation website of
> > regression modeling? Thanks
>
> Unless he thought the exercise would lead to a recognition of a problem
> that would be a learning experience I would have agree; if he was
> serious in the recommendation one would hope it was simply a lack of due
> consideration which would be disappointing at best but if is that
> unfamiliar w/ the subject that would be a major failure it would seem...
>
> Predating the web as a general place I can't say as where there is a
> particularly useful site altho I'm sure there are probably several.
>
> I've always been fond of Raymond H. Myers' book
> _Response_Surface_Methodology_ as being relatively thorough but not
> terribly advanced altho I'll admit much of that is from working w/ him
> lo! so many years ago...
>
> Another that is worthwhile is Box & Jenkins,
> _Statistics_for_Experimenters_ for it's commonsense advice and
> particularly a chapter or two on common pitfalls to avoid.
>
> Both of these, of course, date me as the "old fogey" I have become; I'm
> sure there are many much newer I've never seen that would be just as
> suitable.
>
> --Ok.dpb thanks a lot.

Subject: how to solve this higher polynomial function?

From: John

Date: 26 Sep, 2010 00:58:03

Message: 13 of 17

Walter Roberson <roberson@hushmail.com> wrote in message <hmm5ad$ki$1@canopus.cc.umanitoba.ca>...
> bo wrote:
> > Linear model Poly8:
> > fittedmodel1(x) = p1*x^8 + p2*x^7 + p3*x^6 + p4*x^5 +
> > p5*x^4 + p6*x^3 + p7*x^2 + p8*x + p9
> > Coefficients (with 95% confidence bounds):
> > p1 = -8.739e-010 (-4.795e-008, 4.62e-008)
> > p2 = -1.338e-008 (-1.811e-006, 1.784e-006)
> > p3 = 7.195e-007 (-2.983e-005, 3.127e-005)
> > p4 = 8.171e-006 (-0.001298, 0.001315)
> > p5 = -0.0003242 (-0.01082, 0.01017)
> > p6 = -0.002373 (-0.2801, 0.2753)
> > p7 = -0.02718 (-1.754, 1.699)
> > p8 = -0.3535 (-17.13, 16.42)
> > p9 = 305.7 (239.8, 371.6)
> >
> > Anyone can help me to solve this higher polynomial function ? Then
> > compare the result?Thanks a lot
>
> [27.99708697, 21.78654449+16.78673556*I, -1.715081315+23.37905185*I,
> -25.56879926+16.62652042*I, -32.31309110, -25.56879926-16.62652042*I,
> -1.715081315-23.37905185*I, 21.78654449-16.78673556*I]
>
> The two real roots fit to within 10^(-6)

Subject: how to solve this higher polynomial function?

From: John

Date: 26 Sep, 2010 01:02:05

Message: 14 of 17

You know, I'm getting really tired of these MATLAB tech's who get annoyed at MATLAB user questions (hence, replying with a bunch of sarcasm and !!!!!). MATLAB is not a trivial program to use, even when solving higher order polynomials with uncertainties included. Get it straight. We pay good money for this program, and we expect good responses to our threads for help. If you think you're annoyed, multiply that times 10^5 for us MATLAB users. Peace Out.

Walter Roberson <roberson@hushmail.com> wrote in message <hmm5ad$ki$1@canopus.cc.umanitoba.ca>...
> bo wrote:
> > Linear model Poly8:
> > fittedmodel1(x) = p1*x^8 + p2*x^7 + p3*x^6 + p4*x^5 +
> > p5*x^4 + p6*x^3 + p7*x^2 + p8*x + p9
> > Coefficients (with 95% confidence bounds):
> > p1 = -8.739e-010 (-4.795e-008, 4.62e-008)
> > p2 = -1.338e-008 (-1.811e-006, 1.784e-006)
> > p3 = 7.195e-007 (-2.983e-005, 3.127e-005)
> > p4 = 8.171e-006 (-0.001298, 0.001315)
> > p5 = -0.0003242 (-0.01082, 0.01017)
> > p6 = -0.002373 (-0.2801, 0.2753)
> > p7 = -0.02718 (-1.754, 1.699)
> > p8 = -0.3535 (-17.13, 16.42)
> > p9 = 305.7 (239.8, 371.6)
> >
> > Anyone can help me to solve this higher polynomial function ? Then
> > compare the result?Thanks a lot
>
> [27.99708697, 21.78654449+16.78673556*I, -1.715081315+23.37905185*I,
> -25.56879926+16.62652042*I, -32.31309110, -25.56879926-16.62652042*I,
> -1.715081315-23.37905185*I, 21.78654449-16.78673556*I]
>
> The two real roots fit to within 10^(-6)

Subject: how to solve this higher polynomial function?

From: Ross W

Date: 26 Sep, 2010 05:10:20

Message: 15 of 17

"John " <hernandj72@hotmail.com> wrote in message <i7m62d$gqj$1@fred.mathworks.com>...
> You know, I'm getting really tired of these MATLAB tech's who get annoyed at MATLAB user questions (hence, replying with a bunch of sarcasm and !!!!!). MATLAB is not a trivial program to use, even when solving higher order polynomials with uncertainties included. Get it straight. We pay good money for this program, and we expect good responses to our threads for help. If you think you're annoyed, multiply that times 10^5 for us MATLAB users. Peace Out.
>
> Walter Roberson <roberson@hushmail.com> wrote in message <hmm5ad$ki$1@canopus.cc.umanitoba.ca>...
> > bo wrote:
> > > Linear model Poly8:
> > > fittedmodel1(x) = p1*x^8 + p2*x^7 + p3*x^6 + p4*x^5 +
> > > p5*x^4 + p6*x^3 + p7*x^2 + p8*x + p9
> > > Coefficients (with 95% confidence bounds):
> > > p1 = -8.739e-010 (-4.795e-008, 4.62e-008)
> > > p2 = -1.338e-008 (-1.811e-006, 1.784e-006)
> > > p3 = 7.195e-007 (-2.983e-005, 3.127e-005)
> > > p4 = 8.171e-006 (-0.001298, 0.001315)
> > > p5 = -0.0003242 (-0.01082, 0.01017)
> > > p6 = -0.002373 (-0.2801, 0.2753)
> > > p7 = -0.02718 (-1.754, 1.699)
> > > p8 = -0.3535 (-17.13, 16.42)
> > > p9 = 305.7 (239.8, 371.6)
> > >
> > > Anyone can help me to solve this higher polynomial function ? Then
> > > compare the result?Thanks a lot
> >
> > [27.99708697, 21.78654449+16.78673556*I, -1.715081315+23.37905185*I,
> > -25.56879926+16.62652042*I, -32.31309110, -25.56879926-16.62652042*I,
> > -1.715081315-23.37905185*I, 21.78654449-16.78673556*I]
> >
> > The two real roots fit to within 10^(-6)

Hi John,

You are entitled to good technical support for Matlab. But this newsgroup is not the means to access that support. Instead, see http://www.mathworks.com/support/

This newsgroup is a forum for the Matlab user community. Most of the people replying to questions in this newsgroup are not Matlab techs. Many responses are from experienced and skilled Matlab users. They do this as a service to the community.

They are human, and are not always perfect. But we should cut them plenty of slack when they occasionally grumble, because the FAQ does set out the newsgroup policy, and many initial posts are by people who aren't following the FAQ guidance.

Matlab staff do sometimes post, e.g. Steve Lord. His posts are polite and constructive.

Ross

Subject: how to solve this higher polynomial function?

From: dpb

Date: 26 Sep, 2010 15:01:31

Message: 16 of 17

Ross W wrote:
> "John " <hernandj72@hotmail.com> wrote in message
> <i7m62d$gqj$1@fred.mathworks.com>...
>> You know, I'm getting really tired of these MATLAB tech's who get
>> annoyed at MATLAB user questions (hence, replying with a bunch of
>> sarcasm and !!!!!). MATLAB is not a trivial program to use, even when
>> solving higher order polynomials with uncertainties included. Get it
>> straight. We pay good money for this program, and we expect good
>> responses to our threads for help. If you think you're annoyed,
>> multiply that times 10^5 for us MATLAB users. Peace Out.
...

> You are entitled to good technical support for Matlab. But this
> newsgroup is not the means to access that support. Instead, see
> http://www.mathworks.com/support/
>
> This newsgroup is a forum for the Matlab user community. Most of the
> people replying to questions in this newsgroup are not Matlab techs.
> Many responses are from experienced and skilled Matlab users. They do
> this as a service to the community.
...

To amplify slightly...

c.s-s.m is, despite the TMW-supplied interface portal at their website,
an unmoderated usenet newsgroup that has no official connection w/ TMW.

As Ross says, respondents are virtually all volunteers (some quite
prolific as well as knowledgeable) altho a few TMW employees monitor and
do also provide report as their other workload/job responsibilities
permit. AFAIK, there is no TMW individual directly tasked to respond to
any cssm posting; official support is thru the above online link or via
phone contact or in cases of large installations, local contact.

--

Subject: how to solve this higher polynomial function?

From: Walter Roberson

Date: 26 Sep, 2010 15:45:55

Message: 17 of 17

On 25/09/10 8:02 PM, John wrote:
> You know, I'm getting really tired of these MATLAB tech's who get
> annoyed at MATLAB user questions (hence, replying with a bunch of
> sarcasm and !!!!!). MATLAB is not a trivial program to use, even when
> solving higher order polynomials with uncertainties included. Get it
> straight. We pay good money for this program, and we expect good
> responses to our threads for help. If you think you're annoyed, multiply
> that times 10^5 for us MATLAB users. Peace Out.

John, I have reviewed all the postings in this thread. Prior to your
comment, there were a total of four people involved in this conversation
(including the original poster), *none* of whom have ever worked for
Mathworks -- and, as far as I have been able to determine, none of whom
has ever even received renumeration of any sort from Mathworks, nor even
a discount on purchases of Mathworks software.

You did indeed pay good money for the software, but _none_ of that money
ever went to the contributors to this thread.

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