calcxnu.m

来自「一种基于压缩感知技术的图像重建程序」· M 代码 · 共 33 行

function xnu = CalcXnu(nu)
% xnu = CalcXnu(nu)
% solve (1-nu)/nu = 2 Q(xnu) xnu/q(xnu)  
% Q=\pi^(-1/2)\int_{-\infty}^x exp(-y^2)dy

% check that nu is in range.
if max(nu(:)) >= 1 | min( nu(:)) <= 0,
    disp(' Error in CalcXnu: nu outside (0,1) ')
end

%as xxnu>=0 we add one to the integral of G(xnu) to get Q(xnu)
%this change is seen exhibited in computing pnu

% build table 
xxnu = linspace(0,5,5000);
pnu = (1+erf(xxnu))/2;
eden = exp(-xxnu.^2)./sqrt(pi);       % density of erf
gxnu = xxnu .* pnu ./eden  ;          % left side of (4.2)*2
wnu = (1-nu)./(2.*nu);                % right side of (4.2)/2
xnu = interp1(gxnu,xxnu,wnu);         % x making left = right 

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% Copyright (c) 2006. David Donoho
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% Part of SparseLab Version:100
% Created Tuesday March 28, 2006
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