computeDisc: computes a disconnected correlation function from loops

In hadron: Analysis Framework for Monte Carlo Simulation Data in Physics

computes a disconnected correlation function from loops

Description

The dimension of cf$cf and cf$icf must be dim(Time, S, N), where Time is the time extent, S is the number of samples and N the number of measurements (gauges). cf2 is the same, but needed only for cross-correlators.

Usage

computeDisc(cf, cf2, real = TRUE, real2 = TRUE, smeared = FALSE,
  smeared2 = FALSE, subtract.vev = TRUE, subtract.vev2 = TRUE,
  subtract.equal = TRUE, use.samples, use.samples2, type = "cosh",
  verbose = FALSE)

Arguments

cf	loop data as produced by readcmidisc or readbinarydisc.
cf2	second set of loop data as produced by readcmidisc or readbinarydisc. This is needed for cross-correlators
real	use the real part cf$cf, if set to TRUE, otherwise the imaginary part cf$icf.
real2	use the real part cf2$cf, if set to TRUE, otherwise the imaginary part cf2$icf.
smeared	use the loops instead of the local ones for cf.
smeared2	use the loops instead of the local ones for cf2.
subtract.vev	subtract a vacuum expectation value. It will be estimated as mean over all samples, gauges and times available.
subtract.vev2	subtract a vacuum expectation value for the second set of loops. It will be estimated as mean over all samples, gauges and times available.
subtract.equal	subtract contributions of products computed on identical samples. This will introduce a bias, if set to FALSE for missing cf2 or if cf and cf2 are computed on the same set of random sources.
use.samples	If set to an integer, only the specified number of samples will be used for cf, instead of all samples.
use.samples2	Same like use.samples, but for cf2.
type	The correlation function can either be symmetric or anti-symmetric in time. Anti-symmetric is of course only possible for cross-correlators. In this case with type="cosh" it is assumed to be symmetric, anti-symmetric otherwise.
verbose	Print some debug output, like the VEVs of the loops.

Details

If subtract.vev=TRUE the vev is estimated as the mean over all gauges, samples and times available and subtracted from the original loop data. (Same for subtrac.vev2.

The correlation is computed such as to avoid correlation between equal samples, unless nrSamples is equal to 1.

cf and cf2 must agree in Time, number of gauges and number of samples. Matching of gauges is assumed. If this is not the case results are wrong.

Value

Returns an object of type cf derived from a list with elements cf, an array of dimension dim(N, Time), where N is the number of samples and Time the time extent, integers Time for the time extent, nrStypes and nrObs for the available smearing types and operators, and finally nrSamples, the number of samples used to generate the correlation function cf.

Author(s)

Carsten Urbach, [e-mail]

See Also

readcmidisc, readbinarydisc, bootstrap.cf, add.cf, c.cf

Examples

data(loopdata)
Cpi0v4 <- computeDisc(cf=loopdata, real=TRUE, subtract.vev=TRUE)
Cpi0v4 <- bootstrap.cf(Cpi0v4, boot.R=99, boot.l=1, seed=14556)

hadron documentation built on Sept. 9, 2022, 5:06 p.m.