CLsqFit:IsCoefForced

The IsCoefForced method determines if a specified coefficient has been forced to a value.

Syntax

bForced = CLsqFit:IsCoefForced( nIndex )

bForced = CLsqFit:IsCoefForced( nIndex, nChan )

nIndex is the index of the coefficient in the set of coefficients of the fit. This is a 1-based number.

nChan is an optional parameter that specifies the target channel when fitting multi-channel data

bForced is a boolean true or false value that indicates whether a coefficient was forced..

Remarks

If you are doing a complex fitting procedure and do not remember which coefficients were forced, use this method to query the status of a particular coefficient. To fit all coefficients after some were forced, you can remove all forcing in one step using ResetForcedCoefs.

This method takes a single number for the index of the coefficient to be polled. If you define the basis function in a script, then nIndex is simply an index into your list of coefficients to be fit. Alternatively, when using one of the built-in basis functions the index of the target coefficient is as follows:

n-dimensional polynomial: This method requires use of a helper method to find the coefficient index in the n-dimensional coefficient matrix. See GetPolyCoefIndex.

Hyperplane: The target coefficient can be identified knowing that the first coefficient applies to a constant value,

Example

This example shows how to forcing a coefficient in a 2x2 coefficient polynomial fit. After computing the fit, the cross term between x and y at index 2,2 is removed from the fit by setting it to 0, leaving a fit to an inclined plane rather than a warped plane.

L = new_lsqfit()	-- create the least squares fitting object
L:SetNumCoefs( {2,2} )	-- fit a polynomial with 2 coefs each in 2 dimensions
L:AddPt( -3, 1, 2 )	-- add an (x,y) point
L:AddPt( 4, 5, 3 )	-- add more points...
L:AddPt( 10, 8, 6 )
L:AddPt( 13, 17, 4.5 )
L:AddPt( 15, 12, 4 )
n = GetPolyCoefIndex( { 2, 2, } )	-- find the 2,2 coef in the 2x2 polynomial fit matrix
L:ForceCoef( n, 0.0 )	-- remove the cross-term at the 2,2 position
L:Fit()	-- use 4 coefficients with the 2,2 coef set to 0.0
bForced = L:IsCoefForced( n )	-- check whether the coef at 2,2 has been forced
Printf( "[%d] forced= %d", n, bForced )	-- result: [4] forced= 1

Syntax

Remarks

Example

Related Topics