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class LogisticModel( NonLinearModel )	Source

Logistic Model.

  f( x:p ) = p₀ / ( 1 + exp( ( x - p₁ ) / p₂ ) )

where
  p₀ : amplitude
  p₁ : center
  p₂ : slope

The parameters are initialized at 1.0, 0.0, 1.0.

Examples

lm = LogisticModel( )
print( lm )
Logistic: f( x:p ) = p_0 / ( 1 + exp( ( p_1 - x ) / p_2 ) )
print( lm.npars )
3
print( lm( numpy.arange( 11 ) - 5 ) )
[  3.72665317e-06   3.35462628e-04   1.11089965e-02   1.35335283e-01
   6.06530660e-01   1.00000000e+00   6.06530660e-01   1.35335283e-01
   1.11089965e-02   3.35462628e-04   3.72665317e-06]

Attributes from Model

     npchain, parameters, stdevs, xUnit, yUnit

Attributes from FixedModel

     npmax, fixed, parlist, mlist

Attributes from BaseModel

     npbase, ndim, priors, posIndex, nonZero, tiny, deltaP, parNames

LogisticModel( copy=None, **kwargs )

Logistic response model.

Number of parameters is 3.

Parameters

• copy : LogisticModel
       to be copied
• fixed : None or dictionary of {int:float|Model}
       int index of parameter to fix permanently.
       float|Model values for the fixed parameters.
       Attribute fixed can only be set in the constructor.
       See: FixedModel

copy( )

Copy method.

baseResult( xdata, params )

Returns the result of the model function.

Parameters

• xdata : array_like
       values at which to calculate the result
• params : array_like
       values for the parameters.

basePartial( xdata, params, parlist=None )

Returns the partials at the input value.

Parameters

• xdata : array_like
       values at which to calculate the partials
• params : array_like
       values for the parameters.
• parlist : array_like
       list of indices active parameters (or None for all)

baseDerivative( xdata, params )

Return the derivative df/dx at each xdata (=x).

Parameters

• xdata : array_like
       values at which to calculate the result
• params : array_like
       values for the parameters.

baseName( )

Returns a string representation of the model.

baseParameterUnit( k )

Return the unit of the indicated parameter.

Parameters

• k : int
       parameter number.

Methods inherited from NonLinearModel

• setMixedModel( lindex )
• isMixed( )
• getNonLinearIndex( )
• partial( xdata, param=None, useNum=False )

Methods inherited from Model

• chainLength( )
• isNullModel( )
• isolateModel( k )
• addModel( model )
• subtractModel( model )
• multiplyModel( model )
• divideModel( model )
• pipeModel( model )
• appendModel( model, operation )
• correctParameters( params )
• result( xdata, param=None )
• operate( res, pars, next )
• derivative( xdata, param, useNum=False )
• selectPipe( ndim, ninter, ndout )
• pipe_0( dGd, dHdG )
• pipe_1( dGd, dHdG )
• pipe_2( dGd, dHdG )
• pipe_3( dGd, dHdG )
• pipe_4( dGdx, dHdG )
• pipe_5( dGdx, dHdG )
• pipe_6( dGdx, dHdG )
• pipe_7( dGdx, dHdG )
• pipe_8( dGdx, dHdG )
• pipe_9( dGdx, dHdG )
• shortName( )
• getNumberOfParameters( )
• numDerivative( xdata, param )
• numPartial( xdata, param )
• isDynamic( )
• hasPriors( isBound=True )
• getPrior( kpar )
• setPrior( kpar, prior=None, **kwargs )
• getParameterName( kpar )
• getParameterUnit( kpar )
• getIntegralUnit( )
• setLimits( lowLimits=None, highLimits=None )
• getLimits( )
• hasLimits( fitindex=None )
• unit2Domain( uvalue, kpar=None )
• domain2Unit( dvalue, kpar=None )
• partialDomain2Unit( dvalue )
• nextPrior( )
• getLinearIndex( )
• testPartial( xdata, params, silent=True )
• strictNumericPartial( xdata, params, parlist=None )
• assignDF1( partial, i, dpi )
• assignDF2( partial, i, dpi )
• strictNumericDerivative( xdata, param )

Methods inherited from FixedModel

• select( params )
• selectNames( names )
• expand( xdata, param )

Methods inherited from BaseModel

• checkParameter( param )
• checkPositive( param )
• checkZeroParameter( param )
• isModifiable( )
• basePrior( kpar )
• baseParameterName( kpar )