corrvar.x

Description

corrvar is a TurboRVB utility that computes the global average and standard deviation of energy and variance from block-averaged data, using bootstrap resampling (source comment: "Given in input the block averages of energy and variance, this program computes the global average and standard deviation of these quantities using bootstrap resampling technique").

• Input: fort.21 (bin-by-bin energy \(E\) and weight \(w\)), fort.22 (bin-by-bin \(\langle E^2 \rangle\) -related quantity and weight), parminimized.d (read nwalk from the second line), and standard input (one line: bin_length).

• Output: Standard output only. Prints Energy (weighted average eav0 and bootstrap standard deviation of the mean), Variance square (variance \(\langle E^2 \rangle - \langle E \rangle^2\) estimate and its error), Est. energy error bar, and Est. corr. time (correlation-time estimate and error) in four lines.

• Typical use: After a VMC or optimization run that has produced fort.21 and fort.22, run corrvar with the desired bin length to evaluate energy, variance, error bar, and correlation time. Unlike corrforza/corrforzap (which focus on forces), corrvar is specialized for energy and variance statistics.

The program is serial (no MPI). It has no command-line options; it reads bin_length from standard input (one line) when started.

Input and output

Input

• fort.21 (required): Block (bin) averages of energy e and weight w, one line per bin (two numbers per line). Read with read(11,*) e(i), w(i). If the file is missing or invalid, the program stops with ERROR (101).

• fort.22 (required): Block averages of the variance-related quantity es (\(\langle E^2 \rangle\)) and weight wpip, one line per bin (two numbers per line). Must have the same number of lines as fort.21. If missing or invalid, the program stops with ERROR (102). If wpip ≠ w(i) for any bin, the program prints "warning the measures are not correlated !!!!" and continues.

• parminimized.d (required): First line is skipped; the second line must contain nwalk (walker count). Used to compute the "Est. corr. time" output (eav_*nwalk, esav_*nwalk). If missing or invalid, the program stops with ERROR (100).

• Standard input: One line with bin_length (real). Bin length used in the correlation-time formula (nbin*bin_length*errn²/variance). The program waits for this line; provide it via pipe or redirect (e.g. echo "1.0" | corrvar.x).

Output

• Standard output only (no output files). Lines printed:

  • number of bins read = nbin

  • Energy = eav0 esav (weighted average and bootstrap std dev of the mean)

  • Variance square = eta err (variance estimate and bootstrap error)

  • Est. energy error bar = eta_ err_

  • Est. corr. time = eav_*nwalk esav_*nwalk (correlation time estimate and error)

Notes

File consistency (fort.21 vs fort.22)

• fort.21 and fort.22 must have the same number of lines (same number of bins). The program counts lines by reading both until EOF; a mismatch will cause misaligned data or wrong results.

• The second column of fort.22 (wpip) is expected to equal the weight w in fort.21 for the same bin (correlated measures). If they differ, the warning "the measures are not correlated !!!!" is printed. For correct variance and correlation-time estimates, generate fort.21 and fort.22 from the same binning so that weights match.

parminimized.d and bin_length

• parminimized.d is normally written by the main TurboRVB run (e.g. optimization). Format: first line arbitrary, second line a single integer nwalk. Ensure this file exists in the working directory before running corrvar.

• bin_length must be supplied on standard input. If you run corrvar interactively without redirect, it will wait for one line. Use e.g. echo "bin_length_value" | ./corrvar.x or a script that writes bin_length to stdin.

Bootstrap and memory

• The program runs 1000 bootstrap iterations (nmis=1000) with a fixed random seed. There is no built-in limit on the number of bins; memory use grows with the number of lines in fort.21/fort.22.

Related programs

• TurboRVB main / read_datas: Writes parminimized.d. VMC/optimization runs may also produce fort.21 and fort.22.

• readff, readf, readffn: Tools that read/write fort.21 and related files. The fort.21/fort.22 that corrvar reads are typically produced by these or by the main run.

• corrforza, corrforzap, corrforzap_complex: Bootstrap tools for force correlations. corrvar is specialized for energy, variance, error bar, and correlation time.

• corrcov: Computes covariances from fort.21.* files. corrvar uses only fort.21 and fort.22 for variance and correlation-time estimates.

Troubleshooting

Fatal errors (program stops)

• ERROR: file parminimized.d not found or wrong! — parminimized.d could not be opened or the read (second line) failed. Run the main TurboRVB job first so that parminimized.d is created; check path and permissions.

• ERROR: file fort.21 not found or wrong! — fort.21 could not be opened or a read failed. Ensure a prior VMC/optimization run has produced fort.21 in the working directory.

• ERROR: file fort.22 not found or wrong! — fort.22 could not be opened or a read failed. Ensure a prior run has produced fort.22 with the same number of lines as fort.21.

Warnings

• warning the measures are not correlated !!!! — For at least one bin, the weight wpip read from fort.22 did not equal the weight w from fort.21. The program continues. Check that fort.21 and fort.22 are generated with the same bin structure and weights.

Other notes

• The program has no --help option. Standard input is required for bin_length; without it the program blocks waiting for input.