Quantification of the error propagation. The amount of error, SER, before stitching was evaluated from the original data contained in X (light green box) and the error matrix ΔX (light yellow box). The original data X were processed by Haute Couture to produce the stitched spectra $\hat{\mathbf{S}}$ (light blue box). The error matrix ΔX was combined with the original data X to produce the perturbed data X_± (dark green box). The perturbed data X_± were processed by Haute Couture to produce the stitched spectra ${\hat{\mathbf{S}}}_{\pm }$ (dark blue box), yielding the propagated error $\mathrm{\Delta }{\hat{\mathbf{S}}}_{\pm }$ (dark yellow box). The amount of error SER_± after stitching was evaluated from the stitched original spectra $\hat{\mathbf{S}}$ and the propagated errors $\mathrm{\Delta }{\hat{\mathbf{S}}}_{\pm }$.