LSINFIT

Purpose:

Performs known frequency sine curve fitting using the least squares method.

Syntax:

LSINFIT(series, freq, mode)

series

-

A series, the input sinusoid.

freq

-

A real, the known frequency of the input signal.

mode

-

Optional. An integer, the sinusiod form:

0:

Returns the fitted curve and optionally the coefficients and rms error for the equation:

image\lsinfit01.gif

If the output is directed to variables:

(fit, coef) = lsinfit(series, freq, mode)

 

mode 0 returns coefficients in the form:

coef = {A1, B1, C, RmsError}

1:

(Default). Returns the fitted curve and optionally the coefficients and rms error for the equation:

image\lsinfit02.gif

If the output is directed to variables:

(fit, coef) = lsinfit(series, freq, mode)

 

mode 1 returns coefficients in the form:

coef = {A, theta, C, RmsError}

Returns:

A series and optionally the coefficients and rms error of the fitted curve.

Example:

W1: gsin(1000, .001, 4)

W2: lsinfit(w1, 4, 0)

 

Fits the generated data to the function:

 

image\lsinfit01.gif

Example:

W1: gsin(1000, .001, 4)

(fit, coef) = lsinfit(w1, 4, 1)

 

W2: fit

W3: coef

 

Fits the generated data to the function:

 

image\lsinfit02.gif

 

W2 will contain the fitted curve and W3 will contain the coefficients in the form:

 

coef = {A, theta, C, rmserror}

Remarks:

The known frequency approach to sine curve fitting is commonly used in effective bits calculation. The output of the function is dependant on knowing the frequency of the input series.

 

See SINFIT3 to perform a sinusoid fit with a known or unknown frequency.

 

SINFIT4 to perform an iterative least squares sinusoid fit.

See Also:

EFFBIT

LINFIT

SINFIT

SINFIT3

SINFIT4

References:

IEEE Std 1057-1994 Annex A "Derivation of three parameter (known frequency) sine wave curve fit algorithm"