제가 점을 찍고 그 점을 잇는 곡선에 대한 수식 구하는 방법 문의.

H.L. LEE shared this question 4 years ago
Needs Answer

x축, y축으로 된 2차원 차트에다가 총 7개의 점을 찍어서

그 점들을 모두 잇는 곡선이 필요합니다.

각 점들에 대한 (x,y) 좌표도 알고있기 때문에 표의 형태로 점을 찍을수도있습니다.

그리고 그 곡선에 대한 수식도 필요합니다.

추세선은 의미상 제가 찍은 점들의 추세 만을 파악해서 그래프를 그리는 것 같고...

저는 제가 찍은 7개의 점들이 모두 이어져야 하기 때문에 어쩌면 7개의 점을 모두 잇는 곡선이라는 표현이 더 맞을 수도 있네요.

GeoGebra를 통해서 7개의 점을 잇는 곡선과 그 곡선의 수식을 구하는 방법 알려주시면 감사하겠습니다.

곡선은 대략적으로 ln x의 형태입니다.

엑셀 프로그램을 이용해서 추세선을 그렸더니 제가 찍은 점들을 정확히 연결하지 않더라구요.

Best Answer
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I'm sorry but I don't understand clearly what's your question... I'm just trying to guess.

GeoGebra has a family of commands dedicated to curve fitting / regression. Most of their names all start with Fit, so if you type Fit in the input bar, the autocompletion feature of GeoGebra will list the available commands of the family and the related syntaxes.

Of course GeoGebra is not able to decide automatically which type of regression best fits the points you have drawn in the Graphics View, so you'll have to decide which of these is the most appropriate to use.

The basic syntax common to most of these commands has an unique argument: a list of points, that can be created both in the Graphics View or in the Spreadsheet View. Use the provided links to get to the wiki page of each command and learn more about other possible and more elaborated syntaxes. Once you have decided which form of regression to use, you may enter one of the following commands in the input bar:

Linear regression

Polynomial regression

  • FitPoly[ list of points, degree of polynomial ]: Calculates the regression polynomial of degree n. The higher the degree of your polynomial, the more closely it will be able to fit the points. The degree of the polynomial cannot be greater or equal to the number of points that you are using.
  • Polynomial[ List of points ]: Creates the interpolation polynomial of degree n-1 through the given n points. It fits all the given points, but high order polynomials are difficult to handle, because they are highly oscillatory.

Comments (3)

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2

I'm sorry but I don't understand clearly what's your question... I'm just trying to guess.

GeoGebra has a family of commands dedicated to curve fitting / regression. Most of their names all start with Fit, so if you type Fit in the input bar, the autocompletion feature of GeoGebra will list the available commands of the family and the related syntaxes.

Of course GeoGebra is not able to decide automatically which type of regression best fits the points you have drawn in the Graphics View, so you'll have to decide which of these is the most appropriate to use.

The basic syntax common to most of these commands has an unique argument: a list of points, that can be created both in the Graphics View or in the Spreadsheet View. Use the provided links to get to the wiki page of each command and learn more about other possible and more elaborated syntaxes. Once you have decided which form of regression to use, you may enter one of the following commands in the input bar:

Linear regression

Polynomial regression

  • FitPoly[ list of points, degree of polynomial ]: Calculates the regression polynomial of degree n. The higher the degree of your polynomial, the more closely it will be able to fit the points. The degree of the polynomial cannot be greater or equal to the number of points that you are using.
  • Polynomial[ List of points ]: Creates the interpolation polynomial of degree n-1 through the given n points. It fits all the given points, but high order polynomials are difficult to handle, because they are highly oscillatory.

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1

Thank you for your kind explanation.

Perhaps you used an automatic interpreter that cause more confusion to understand my question.

My question was to draw a line and also estimate the closest formula, for seven points on the x-y axis sheet.

The coordinate of the seven points are known, and continuous, and the line must past the seven points.

Anyway, I will first try to do as your advisory.

Once again, thank you for your quote :)

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1

try spline()

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