Hi,
I have one vector of variable y and four vectors of x1, x2,
x3 and x4. And I need to aproximate y by least squares
method from all vectors x. Example:
y --------- x1 --------- x2 --------- x3 ---------- x4
I now this can be accomplished with function "polyfit", but
I didn't understand from help, how should I do it. Should I
make matrice from those x vectors and present that matrice
as x in "polyfit" function?
On Wed, 14 May 2008 19:48:02 +0000 (UTC), "beda meda"
<b.meda@centrum.cz> wrote:
>Hi,
>I have one vector of variable y and four vectors of x1, x2,
>x3 and x4. And I need to aproximate y by least squares
>method from all vectors x. Example:
>
>y --------- x1 --------- x2 --------- x3 ---------- x4
>
>104 ---- 145.455 ---- 446.493 ---- 1381.006 ---- 2472.230
>104 ---- 142.857 ---- 415.004 ---- 1556.626 ---- 2553.037
>104 ---- 145.455 ---- 540.619 ---- 1778.841 ---- 2539.434
>105 ---- 150.943 ---- 405.916 ---- 1307.187 ---- 2483.152
>104 ---- 142.857 ---- 420.071 ---- 1764.712 ---- 2553.209
>105 ---- 142.857 ---- 445.416 ---- 1519.577 ---- 2498.646
>103 ---- 148.148 ---- 316.140 ---- 1728.223 ---- 2544.723
>102 ---- 148.148 ---- 372.026 ---- 1529.687 ---- 2473.594
>106 ---- 235.294 ---- 361.520 ---- 1493.840 ---- 2602.597
>106 ---- 228.571 ---- 427.001 ---- 1778.426 ---- 2571.960
>106 ---- 235.294 ---- 434.787 ---- 1505.175 ---- 2753.895
>
>I now this can be accomplished with function "polyfit", but
>I didn't understand from help, how should I do it. Should I
>make matrice from those x vectors and present that matrice
>as x in "polyfit" function?
>
>Thanks for help
The built-in operator "\" will do this for you.
-Dick Startz
On May 15, 7:48=A0am, "beda meda" <b.m...@centrum.cz> wrote:
> Hi,
> I have one vector of variable y and four vectors of x1, x2,
> x3 and x4. And I need to aproximate y by least squares
> method from all vectors x. Example:
>
> y --------- x1 --------- x2 --------- x3 ---------- x4
>
> 104 ---- 145.455 ---- 446.493 ---- 1381.006 ---- 2472.230
> 104 ---- 142.857 ---- 415.004 ---- 1556.626 ---- 2553.037
> 104 ---- 145.455 ---- 540.619 ---- 1778.841 ---- 2539.434
> 105 ---- 150.943 ---- 405.916 ---- 1307.187 ---- 2483.152
> 104 ---- 142.857 ---- 420.071 ---- 1764.712 ---- 2553.209
> 105 ---- 142.857 ---- 445.416 ---- 1519.577 ---- 2498.646
> 103 ---- 148.148 ---- 316.140 ---- 1728.223 ---- 2544.723
> 102 ---- 148.148 ---- 372.026 ---- 1529.687 ---- 2473.594
> 106 ---- 235.294 ---- 361.520 ---- 1493.840 ---- 2602.597
> 106 ---- 228.571 ---- 427.001 ---- 1778.426 ---- 2571.960
> 106 ---- 235.294 ---- 434.787 ---- 1505.175 ---- 2753.895
>
> I now this can be accomplished with function "polyfit", but
> I didn't understand from help, how should I do it. Should I
> make matrice from those x vectors and present that matrice
> as x in "polyfit" function?
>
> Thanks for help
Polyfit's the wrong one for this.
help mldivide
Take special notice of the 2nd paragraph which talks about least
squares
coef=3D[x1 x2 x3 x4]\y
NZTideMan <mulgor@gmail.com> wrote in message
<08bcf48a-93cf-4651-a763-b00d212b1f2d@c19g2000prf.googlegroups.com>...
> On May 15, 7:48=A0am, "beda meda" <b.m...@centrum.cz> wrote:
> > Hi,
> > I have one vector of variable y and four vectors of x1, x2,
> > x3 and x4. And I need to aproximate y by least squares
> > method from all vectors x. Example:
> >
> > y --------- x1 --------- x2 --------- x3 ---------- x4
> >
> > 104 ---- 145.455 ---- 446.493 ---- 1381.006 ---- 2472.230
> > 104 ---- 142.857 ---- 415.004 ---- 1556.626 ---- 2553.037
> > 104 ---- 145.455 ---- 540.619 ---- 1778.841 ---- 2539.434
> > 105 ---- 150.943 ---- 405.916 ---- 1307.187 ---- 2483.152
> > 104 ---- 142.857 ---- 420.071 ---- 1764.712 ---- 2553.209
> > 105 ---- 142.857 ---- 445.416 ---- 1519.577 ---- 2498.646
> > 103 ---- 148.148 ---- 316.140 ---- 1728.223 ---- 2544.723
> > 102 ---- 148.148 ---- 372.026 ---- 1529.687 ---- 2473.594
> > 106 ---- 235.294 ---- 361.520 ---- 1493.840 ---- 2602.597
> > 106 ---- 228.571 ---- 427.001 ---- 1778.426 ---- 2571.960
> > 106 ---- 235.294 ---- 434.787 ---- 1505.175 ---- 2753.895
> >
> > I now this can be accomplished with function "polyfit", but
> > I didn't understand from help, how should I do it. Should I
> > make matrice from those x vectors and present that matrice
> > as x in "polyfit" function?
> >
> > Thanks for help
>
> Polyfit's the wrong one for this.
> help mldivide
> Take special notice of the 2nd paragraph which talks about
least
> squares
> coef=3D[x1 x2 x3 x4]\y
I think this is what I need, thanks!
---------------------------
to Dick:
You meant I should divide matrice x by y and then use
polyfit? Or if not, what did you mean?
On Wed, 14 May 2008 21:05:05 +0000 (UTC), "beda meda"
<b.meda@centrum.cz> wrote:
>NZTideMan <mulgor@gmail.com> wrote in message
><08bcf48a-93cf-4651-a763-b00d212b1f2d@c19g2000prf.googlegroups.com>...
>> On May 15, 7:48=A0am, "beda meda" <b.m...@centrum.cz> wrote:
>> > Hi,
>> > I have one vector of variable y and four vectors of x1, x2,
>> > x3 and x4. And I need to aproximate y by least squares
>> > method from all vectors x. Example:
>> >
>> > y --------- x1 --------- x2 --------- x3 ---------- x4
>> >
>> > 104 ---- 145.455 ---- 446.493 ---- 1381.006 ---- 2472.230
>> > 104 ---- 142.857 ---- 415.004 ---- 1556.626 ---- 2553.037
>> > 104 ---- 145.455 ---- 540.619 ---- 1778.841 ---- 2539.434
>> > 105 ---- 150.943 ---- 405.916 ---- 1307.187 ---- 2483.152
>> > 104 ---- 142.857 ---- 420.071 ---- 1764.712 ---- 2553.209
>> > 105 ---- 142.857 ---- 445.416 ---- 1519.577 ---- 2498.646
>> > 103 ---- 148.148 ---- 316.140 ---- 1728.223 ---- 2544.723
>> > 102 ---- 148.148 ---- 372.026 ---- 1529.687 ---- 2473.594
>> > 106 ---- 235.294 ---- 361.520 ---- 1493.840 ---- 2602.597
>> > 106 ---- 228.571 ---- 427.001 ---- 1778.426 ---- 2571.960
>> > 106 ---- 235.294 ---- 434.787 ---- 1505.175 ---- 2753.895
>> >
>> > I now this can be accomplished with function "polyfit", but
>> > I didn't understand from help, how should I do it. Should I
>> > make matrice from those x vectors and present that matrice
>> > as x in "polyfit" function?
>> >
>> > Thanks for help
>>
>> Polyfit's the wrong one for this.
>> help mldivide
>> Take special notice of the 2nd paragraph which talks about
>least
>> squares
>> coef=3D[x1 x2 x3 x4]\y
>
>I think this is what I need, thanks!
>---------------------------
>
>to Dick:
>You meant I should divide matrice x by y and then use
>polyfit? Or if not, what did you mean?
>
>But thank you too!
Basically, I was saying the same thing NZTide said. The coefficients
are
"beda meda" <b.meda@centrum.cz> wrote in message
<g0ffli$fv3$1@fred.mathworks.com>...
> Hi,
> I have one vector of variable y and four vectors of x1, x2,
> x3 and x4. And I need to aproximate y by least squares
> method from all vectors x. Example:
>
> y --------- x1 --------- x2 --------- x3 ---------- x4
>
> 104 ---- 145.455 ---- 446.493 ---- 1381.006 ---- 2472.230
> 104 ---- 142.857 ---- 415.004 ---- 1556.626 ---- 2553.037
> 104 ---- 145.455 ---- 540.619 ---- 1778.841 ---- 2539.434
> 105 ---- 150.943 ---- 405.916 ---- 1307.187 ---- 2483.152
> 104 ---- 142.857 ---- 420.071 ---- 1764.712 ---- 2553.209
> 105 ---- 142.857 ---- 445.416 ---- 1519.577 ---- 2498.646
> 103 ---- 148.148 ---- 316.140 ---- 1728.223 ---- 2544.723
> 102 ---- 148.148 ---- 372.026 ---- 1529.687 ---- 2473.594
> 106 ---- 235.294 ---- 361.520 ---- 1493.840 ---- 2602.597
> 106 ---- 228.571 ---- 427.001 ---- 1778.426 ---- 2571.960
> 106 ---- 235.294 ---- 434.787 ---- 1505.175 ---- 2753.895
>
> I now this can be accomplished with function "polyfit", but
> I didn't understand from help, how should I do it. Should I
> make matrice from those x vectors and present that matrice
> as x in "polyfit" function?
>
> Thanks for help
No. Polyfit cannot do this. You can either
use backslash, or download my polyfitn
from the file exchange.
richardstartz@comcast.net wrote in message
<q3lm24d6102eq72sfa2tvb226bosoo2tha@4ax.com>...
> On Wed, 14 May 2008 21:05:05 +0000 (UTC), "beda meda"
> <b.meda@centrum.cz> wrote:
>
> >NZTideMan <mulgor@gmail.com> wrote in message
>
><08bcf48a-93cf-4651-a763-b00d212b1f2d@c19g2000prf.googlegroups.com>...
> >> On May 15, 7:48=A0am, "beda meda" <b.m...@centrum.cz>
wrote:
> >> > Hi,
> >> > I have one vector of variable y and four vectors of
x1, x2,
> >> > x3 and x4. And I need to aproximate y by least squares
> >> > method from all vectors x. Example:
> >> >
> >> > y --------- x1 --------- x2 --------- x3 ---------- x4
> >> >
> >> > 104 ---- 145.455 ---- 446.493 ---- 1381.006 ---- 2472.230
> >> > 104 ---- 142.857 ---- 415.004 ---- 1556.626 ---- 2553.037
> >> > 104 ---- 145.455 ---- 540.619 ---- 1778.841 ---- 2539.434
> >> > 105 ---- 150.943 ---- 405.916 ---- 1307.187 ---- 2483.152
> >> > 104 ---- 142.857 ---- 420.071 ---- 1764.712 ---- 2553.209
> >> > 105 ---- 142.857 ---- 445.416 ---- 1519.577 ---- 2498.646
> >> > 103 ---- 148.148 ---- 316.140 ---- 1728.223 ---- 2544.723
> >> > 102 ---- 148.148 ---- 372.026 ---- 1529.687 ---- 2473.594
> >> > 106 ---- 235.294 ---- 361.520 ---- 1493.840 ---- 2602.597
> >> > 106 ---- 228.571 ---- 427.001 ---- 1778.426 ---- 2571.960
> >> > 106 ---- 235.294 ---- 434.787 ---- 1505.175 ---- 2753.895
> >> >
> >> > I now this can be accomplished with function
"polyfit", but
> >> > I didn't understand from help, how should I do it.
Should I
> >> > make matrice from those x vectors and present that
matrice
> >> > as x in "polyfit" function?
> >> >
> >> > Thanks for help
> >>
> >> Polyfit's the wrong one for this.
> >> help mldivide
> >> Take special notice of the 2nd paragraph which talks about
> >least
> >> squares
> >> coef=3D[x1 x2 x3 x4]\y
> >
> >I think this is what I need, thanks!
> >---------------------------
> >
> >to Dick:
> >You meant I should divide matrice x by y and then use
> >polyfit? Or if not, what did you mean?
> >
> >But thank you too!
>
> Basically, I was saying the same thing NZTide said. The
coefficients
> are
>
> coef=[x1 x2 x3 x4]\y;
>
> The approximated value is
>
> [x1 x2 x3 x4]*coef;
OK, thanks.
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