function [u] = spm_uc_Bonf(a,df,STAT,S,n)
% corrected critical height threshold at a specified significance level
% FORMAT [u] = spm_uc_Bonf(a,df,STAT,S,n)
% a     - critical probability - {alpha}
% df    - [df{interest} df{residuals}]
% STAT  - Statisical feild
%		'Z' - Gaussian feild
%		'T' - T - feild
%		'X' - Chi squared feild
%		'F' - F - feild
% S     - Voxel count
% n     - abs(n), number of conjoint SPMs
%
% u     - critical height {corrected}
%
%___________________________________________________________________________
%
% spm_uc returns the corrected critical threshold at a specified significance
% level (a). If n > 1 a conjunction the probability over the n values of the 
% statistic is returned.
%
% If abs(n) > 1, a P-value for a minimum of n values of the statistic 
% is returned.  If n>0, the P-value assesses the conjunction null
% hypothesis of one or more of the null hypotheses being true.  If n<0,
% then the P-value assess the global null of all nulls being true. 
%___________________________________________________________________________
% @(#)spm_uc_Bonf.m	1.6 Thomas Nichols 04/06/30

if n>0
  Cnj_n = 1;       % Inf on Conjunction Null
else
  Cnj_n = abs(n);  % Inf on Global Null
end

u   = spm_u((a/S).^(1/Cnj_n),df,STAT);