;REDO THE LEAST SQUARES FIT, DOING A CHI SQUARES FIT INSTEAD... ;SUBSCRIPT ALL CHI FIT ARRAYS BY _CHI... s = fltarr(3,4) m=4 n=3 ;FROM THE LEAST SQUARES FIT, WE FIND... sigma = sqrt( 20.d0) time = double([5,7,9,11]) ;time=time-8. s[0,*]=1. s[1,*]=time s[2,*]=time^2 tdata= double([142,168,211,251]) ;DERIVE THE DESIGN MATRIX; DIVIDE THE DATA MATRIX BY SIGMA... ;ALL CHISQ QUANTITIES ARE SUBSCRIPTED BY _CHI... s_chi = s / sigma t_chi = t / sigma ss_chi=transpose(s_chi)##s_chi st_chi = transpose(s_chi)##t_chi ss_chi_i = invert(ss_chi) a_chi = ss_chi_i ## st_chi bt_chi = s_chi ## a_chi dely_chi = t_chi - bt_chi bt = s ## a_chi dely = t - bt sigmasq = total( dely^2)/(m-n) chisq = total((t_chi - bt_chi)^2) reduced_chisq = total((t_chi - bt_chi)^2)/(m-n) dc_chi = ss_chi_i[ (n+1) * indgen(n)] sigdcsq_ch = chisq * dc_chi sigdc_ch = sqrt(sigdcsq_ch) sigdcsq_nm = dc_chi sigdc_nm = sqrt(sigdcsq_nm) ncov_chi = ss_chi_i/sqrt(dc_chi # dc_chi)