Looks like stepsize plays no role in err=2 sigmas Following is an old one with original sigmas, much too small - set to sigI Clean this up if decided to go with kludged sigF input. For err=2 mode=1 0.104 2.036 2.179 0.1429 0.1 2.043 0.207 1.198 1.354 0.1565 0.0193 65.77 0.311 0.9409 0.9673 0.02643 0.0127 4.33 0.415 1.245 1.379 0.1339 0.0148 81.91 0.519 0.4568 0.4559 -0.0009956 0.005 0.03965 0.622 0.1763 0.1603 -0.01595 0.005 10.18 0.726 0.4306 0.3831 -0.04751 0.005 90.3 0.83 0 0.03927 0.03927 0.005 61.69 0.934 0.5835 0.5609 -0.02259 0.005 20.41 1.037 0.1288 0.09778 -0.03104 0.005 38.54 1.141 0.1371 0.09589 -0.04121 0.005 67.94 1.245 0.3157 0.3485 0.03282 0.005 43.08 chi2red = 48.62 sigma^2 input values