Regression on data

Author

1-Visitor

Could you be more specific on how I have to do it. I am totally lost. Those guides I find online seem very complicated compared to my level. I thougt I could just choose polyfit(x,y) and then it would give me the function.

R

RichardJ

19-Tanzanite

Polyfit makes it a little simpler, but it doesn't change much.

1_ptc-polyfit-mcdx.zip

25-Diamond I

Using linear or spline interpolation you won't see an explicit equation but you can use the result like any other function:

WE

BTW, in case you wonder why we all don't use the sheet you posted but instead used the sheet where Fred retyped the part of the data which was visible from the picture you posted.

Fred, Richard and me - neither of us has Prime 3.1 installed (just 3.0) and so we are unable to open files in P3.1 format. As you can't save in P3.0 format, screenshots or pdf-prints are the only way to communicate your problem/worksheet.

Of course your Prime 3.1 can read our P3.0 files.

V

ValeryOchkov

24-Ruby IV

If we have one equation better use not the Find but the root function

25-Diamond I

Root sure is an alternative, but I don't see why it should be "better".

Unless you are using Prime Express and can't use a solve block, of course.

Author

1-Visitor

FredKohlhepp‌ I didn't see your attached file at first. I am sorry about that.

In the line with vs:=regress(x,y,5) what is does the 5 mean?

In the line with Fn(x,,vs): I have no clue what is happening after the equation sign. Is it somehting you have typed, or is this given by Mathcad in someway?

I appreciate the help you guys are giving me, even though I am a asking a lot of questions.

R

RichardJ

19-Tanzanite

In the line with vs:=regress(x,y,5) what is does the 5 mean?

The order of the polynomial that regress fits to the data.

In the line with Fn(x,,vs): I have no clue what is happening after the equation sign. Is it somehting you have typed, or is this given by Mathcad in someway?

The regress function returns the coefficients of a polynomial in the vector vs. The coefficients start at the fourth element of the vector (the first three elements are other information; you can ignore them). The summation represents that polynomial: vs0*x^0 + vs1*x^1 + vs2*x^2 + ...

Author

1-Visitor

Thanks a lot.

It seems a lot more difficult tthan wordmath.

25-Diamond I

Tommi Lauridsen wrote:

Thanks a lot.

It seems a lot more difficult tthan wordmath.

Whats wordmath?

Author

1-Visitor

WordMath is an add-on for Word. It is actually working very well for a lot of things.

Author

1-Visitor

I can try doing it in the weekend

1_PumpekarakteristikWORD.docx

Author

1-Visitor

This is an example of how it could be done in WordMat . It is done very quick, and there is some autogenerated danish word in the document. Hope it makes sense to you.

I have found another another problem in MathCad. I can't multiply two matrices? It seems like instead of multiplying it is adding all of the numbers in the matrices each of them and multiplying them afterwards. I have no problems if I am dividing them?

I have attached a file showing imy problem. I get only one solution. Instead of a solution for each row?

25-Diamond I

You are multiplying two vectors and what you get is the scalar product - so all ist OK.

You want a vector as result where the first component is the product of the first components of the two initial vectors. Thats not what matrix or vector product ist meant for from a mathematical point of view.

But Mathcad has a solution for this which is called vectorization. You have to vectorize the product (matrix palette, they symbol is the right arrow) to get what you want to see.

R