Data Dimensionality with SVD. The linear dimensionality of experimental data space is measured with Singular Value Decomposition. a) The E. coli model has 313 reactions and 139 degrees of freedom. The isotopomer fragments were computed for a random sample of flux distributions and plotted in the 186 dimensional space of simulated measurements. The upper bound on the number of degrees of freedom in this space was determined by singular value decomposition on the samples. The number of singular values was counted until the magnitude of the next singular value fell below the instrument threshold. b) The number of significant singular values at different levels of experimental error is tabulated for various labeling patterns, with values ranging from 26 to 100.