Palamedes: PFML_Fit: initial value

初期値をきめるために。

 

 

>> help PAL_PFML_Fit

 PAL_PFML_Fit   Fit a psychometric function to data using a Maximum 

     Likelihood criterion.

：

 

'searchGrid': Either a 1x4 vector containing initial guesses for free 

        parametervalues and fixed values for fixed parameters [threshold 

        slope guess-rate lapse-rate] or a structure with vector fields 

        .alpha, .beta, .gamma, .lambda collectively defining a 4D parameter 

        grid through which to perform a brute-force search for initial 

        guesses (using PAL_PFML_BruteForceFit). Fields for fixed parameters 

        should be scalars equal to the fixed value. Note that choices made 

        here have a large effect on processing time and memory usage.

 

    'paramsFree': 1x4 vector coding which of the four parameters in 

        paramsValue are free parameters and which are fixed parameters 

        (1: free, 0: fixed).

 

 

：

Full example:

 

    options = optimset('fminsearch');

    PF = @PAL_Logistic;

    StimLevels = [-3:1:3];

    NumPos = [55 55 66 75 91 94 97];    %observer data

    OutOfNum = 100.*ones(size(StimLevels));

    searchGrid.alpha = [-1:.01:1];    %structure defining grid to　<--- この部分以下で範囲を設定

    searchGrid.beta = 10.^[-1:.01:2]; %search for initial values　

    searchGrid.gamma = .5;

    searchGrid.lambda = [0:.005:.06];　

 

    %or (not advised):

    % searchGrid = [0 1 .5 0.01];       %Guesses

 

    paramsFree = [1 1 0 1]

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