Approximation functions

This window is for creation of approximation or smallest error functions.

Approximation functions contain the data points (Gauss-Elimination), smallest error function have the smallest error-square. .

Dependent on the function type there will be a minimum of 2, maximum of 3 (Exponential approximation), 20 (Approximation polynom) or 1000 (smallest error functions) data points accepted.

They must be entered in the text field of the dialog, syntax is X,Y without blanks. Insertion in the list takes place with pressing the button 'Add' or hitting 'Return'.

The option 'from current graph' loads the data points from the current active graph. For this the program selects automatically the number of points from the field "Number points". Which points actually have been used can be seen when the dialog is reopened after creation of the function.

Entries in the field 'Name' will be inserted as the label of the function.

The created function will always be appended to the existing functions.

Polynom

This option calculates a approximation function that is based on a Polynom.

Example:

With the setting 'Name' "tst" and the data points 0,0 1,1 2,4 the result is

tst = x^2

Linear

This option calculates a linear function based on the smallest error squares.

Exponential function

This option calculates a exponential function based on the smallest error squares.

Power function

This option calculates a power function based on the smallest error squares

Parabel

This option calculates a parabel (square) function based on the smallest error squares.

Exponential approximation

This option calculates a approximation function that is based on the exponential function. Three data points need to be entered, the X value of the 3 point has to be x3 = x2+(x2-x1).