function X2 = chisquared_table(P,v)%CHISQUARED_TABLE computes the "percentage points" of the%chi-squared distribution, as in Abramowitz & Stegun Table 26.8%   X2 = CHISQUARED_TABLE( P, v ) returns the value of chi-squared %   corresponding to v degrees of freedom and probability P.%   P is the probability that the sum of squares of v unit-variance%   normally-distributed random variables is <= X2.%   P and v may be matrices of the same size size, or either %   may be a scalar.%%   e.g., to find the 95% confidence interval for 2 degrees%   of freedom, use CHISQUARED_TABLE( .95, 2 ), yielding 5.99,%   in agreement with Abramowitz & Stegun's Table 26.8%%   This result can be checked through the function%   CHISQUARED_PROB( 5.99, 2 ), yielding 0.9500%%   The familiar 1.96-sigma confidence bounds enclosing 95% of%   a 1-D gaussian is found through %   sqrt( CHISQUARED_TABLE( .95, 1 )), yielding 1.96%%   See also CHISQUARED_PROB%%Peter R. Shaw, WHOI%Leslie Rosenfeld, MBARI% References: Press et al., Numerical Recipes, Cambridge, 1986;% Abramowitz & Stegun, Handbook of Mathematical Functions, Dover, 1972.% Peter R. Shaw, Woods Hole Oceanographic Institution% Woods Hole, MA 02543  pshaw@whoi.edu% Leslie Rosenfeld, MBARI% Last revision: Peter Shaw, Oct 1992: fsolve with version 4% ** Calls function CHIAUX  **% Computed using the Incomplete Gamma function,% as given by Press et al. (Recipes) eq. (6.2.17)[mP,nP]=size(P);[mv,nv]=size(v);if mP~=mv | nP~=nv,   if mP==1 & nP==1,    P=P*ones(mv,nv);  elseif mv==1 & nv==1,    v=v*ones(mP,nP);  else    error('P and v must be the same size')  endend[m,n]=size(P);  X2 = zeros(m,n);for i=1:m, for j=1:n,  if v(i,j)<=10,    x0=P(i,j)*v(i,j);  else   x0=v(i,j);  end% Note: "old" and "new" calls to fsolve may or may not follow % Matlab version 3.5 -> version 4 (so I'm keeping the old call around...)%   X2(i,j) = fsolve('chiaux',x0,zeros(16,1),[v(i,j),P(i,j)]); %(old call)   X2(i,j) = fsolve('chiaux',x0,zeros(16,1),[],[v(i,j),P(i,j)]); endend