Dear CP2k developers, I used subroutine "cp_fm_invert" to calculate the determinant and the inverse of a matrix, and found that sometimes there is a discrepancy on the sign of determinant. For example, both MATLAB and GSL gave 0.985956424462 for the following 12x12 matrix in agreement with CP2k. However, on the 11x11 matrix, CP2k's solution of -0.167690021767 is opposite to the correct answer of 0.167690021767. I am wondering what "cp_fm_invert" actually calculates, or is it a possible bug? Thanks. Hanning Chen Department of Chemistry Northwestern University Evanston, IL 60208 . 12x12 Matrix: 0.999199 -0.000672 0.000280 -0.000199 0.000109 0.000631 0.000253 -0.001142 -0.000124 0.000693 0.002188 0.001618 0.000663 0.999305 0.000027 0.001681 0.002113 0.000150 0.001346 0.001019 -0.001870 -0.002973 -0.002747 -0.000586 0.000393 0.000051 0.999509 0.000319 0.000077 -0.000148 0.000330 0.000475 -0.000365 -0.000596 -0.000727 -0.000258 -0.000697 -0.001284 0.000246 0.999205 -0.000497 0.001035 0.000528 -0.002163 -0.000202 0.001603 0.004558 0.003429 -0.001479 -0.001894 0.000813 -0.000757 0.998991 0.001442 0.000495 -0.003395 0.000079 0.002597 0.006290 0.004653 -0.000765 0.000279 0.000209 -0.001416 -0.001597 0.999530 -0.001164 -0.001024 0.001694 0.002543 0.002156 0.000355 -0.001398 -0.000534 0.000395 -0.002065 -0.002184 0.000651 0.998659 -0.002636 0.001748 0.004101 0.005792 0.002838 0.000005 -0.001615 0.000392 0.001506 0.002156 0.001101 0.002075 0.998868 -0.002404 -0.002069 0.000952 0.002395 0.001943 0.001060 -0.000682 0.002348 0.002288 -0.001045 0.000926 0.003703 0.997828 -0.004828 -0.007578 -0.004153 0.001610 0.002764 -0.000875 0.000422 0.000141 -0.002073 -0.001358 0.004145 0.001031 0.997477 -0.008057 -0.006371 -0.000906 0.003813 -0.000284 -0.004163 -0.005091 -0.002425 -0.005616 0.001218 0.006627 0.005908 0.998421 -0.005509 -0.001534 0.002024 -0.000007 -0.004128 -0.004912 -0.001126 -0.004233 -0.001146 0.005358 0.006780 0.003616 0.998459 11x11 Matrix: 0.959602 -0.028013 0.030147 -0.022069 -0.073733 -0.003573 -0.019387 -0.068397 0.051648 0.094577 0.085067 -0.029391 0.978389 0.022461 -0.017467 -0.055452 -0.000449 -0.014748 -0.050543 0.039101 0.070648 0.061971 0.030718 0.021680 0.975750 0.018031 0.057802 0.002701 0.015084 0.054095 -0.042206 -0.073863 -0.066378 -0.022619 -0.014997 0.016342 0.986592 -0.039914 -0.005875 -0.009658 -0.037342 0.027425 0.047091 0.047450 -0.077915 -0.054333 0.058828 -0.045723 0.854288 -0.004938 -0.037919 -0.132490 0.101722 0.181213 0.163345 -0.001933 -0.003550 0.001547 0.002798 -0.005498 0.998936 -0.005081 -0.005224 0.006538 0.008079 0.008798 -0.019817 -0.013630 0.015114 -0.012611 -0.037144 0.002330 0.989544 -0.031761 0.023120 0.046730 0.038984 -0.068450 -0.048605 0.051127 -0.039863 -0.129351 -0.004394 -0.035990 0.881004 0.095143 0.159551 0.146483 0.056884 0.039437 -0.041209 0.033939 0.105766 0.001131 0.030483 0.092134 0.925001 -0.122981 -0.115925 0.090775 0.063626 -0.068649 0.057393 0.173166 0.004885 0.045038 0.160300 -0.130325 0.782704 -0.193978 0.079091 0.056981 -0.059929 0.045185 0.150758 0.002755 0.042173 0.137141 -0.108773 -0.189918 0.829109