rtdists

0.12-x

Released September 2026

• Added racing diffusion model (RDM), see ?RDM. Thanks to Kianté Fernandez (#23).
• Fixed pwald (and thereby pRDM) losing precision when 2*b*v/s^2 is large (e.g., with s = 0.1), and returning 0 instead of 1 for rt = Inf. Thanks to Gidon Frischkorn for finding this (#26).
• Fixed a rather large bug in pdiffusion that occurred whenever RTs were not ordered. Thanks to Kianté Fernandez (#21).
• Large speed improvement to diffusion model functions. Change is probably most noticeable in ddiffusion when called with large number of RTs and varying parameters. Thanks to Kianté Fernandez (#21).
• Fixed bugs in the lognormal and gamma single-accumulator LBA functions (dlba_lnorm, plba_lnorm, dlba_gamma, plba_gamma) that produced incorrect results when any element of A was below 1e-10 (the A_small branch). The lognormal functions used max instead of min in several intermediate calculations, plba_lnorm did not apply rem_t0 in the A_small branch, and the gamma functions used full-length vectors instead of subsetted ones.
• Fixed dlba_frechet and plba_frechet returning 0 for A = 0 (no start-point variability). They now use the closed form for a fixed start point, as the other distributions do (#4).
• Fixed non-monotonic behaviour in pdiffusion for starting values near the boundary (#13). The PDE boundary conditions at t=0 differed from the F_limit initial condition, causing incorrect interpolation near z = a (or z = 0).

0.11-6

Released June 2026.

• Included a check in rdiffusion preventing RTs < t0. Thanks to Andrew Heathcote for reporting this.

0.11-x

Released March 2020.

• Faster calculation of diffusion density (ddiffusion) and CDF (pdiffusion) in case exactly one set of parameters is passed. In this case, some checks are skipped now leading to a 40% to 50% speed increase.
• Diffusion quantile function qdiffusion should be faster now when it is called with many probabilities for the same response.
• Diffusion quantile function qdiffusion has a new argument max_diff which allows to control the minimally acceptable difference between desired and obtained probabilities.
• Added experimental method = "qdiffusion" to rdiffusion() which obtains random derivates via the quantile function and runif(). This method is for the time being a lot slower than the native one (i.e., method = "fastdm").
• Tests should work even if options("stringsAsFactors" = FALSE) (in preparation for R 4.0).
• 0.11-3: removed bug that diffusion functions failed if there were NAs in the parameters.
• 0.11-3: uses RCPP STRICT_R_HEADERS: https://github.com/rtdists/rtdists/pull/14

0.10-x

Released October 2019.

• Removed another argument passing bug that occurred when using args.dist and more than two drift rates. Reported by Glen Livingston Jr.
• Removed issue in vignette due to breaking change in a tidyverse package.

0.9-x

Released August 2018.

• Removed bug in dLBA and pLBA that prevented correct usage of trial-wise parameters. This bug always appeared when data with more than one response was present together with trial-wise parameters. In the following example the first call should be identical to the second and third call:

  x1 <- dLBA(rt=c(1,1), response=c(1,2), A=1,b=list(c(1,3),c(2,4)),
          t0=0.1, mean_v=c(3,3), sd_v=c(1,1),distribution="norm")
  x2a <- dLBA(rt=c(1), response=c(1), A=1,b=list(c(1),c(2)),
          t0=0.1,mean_v=c(3,3),sd_v=c(1,1),distribution="norm")
  x2b <- dLBA(rt=c(1), response=c(2), A=1,b=list(c(3),c(4)),
          t0=0.1,mean_v=c(3,3),sd_v=c(1,1),distribution="norm")
  all(x1 == c(x2a, x2b)) ## should be TRUE

0.8-x

Released December 2017 & updated June 2018.

• Removed bug preventing args.list (e.g., posdrift) to be passed correctly in dLBA, pLBA, qLBA, and rLBA. Thanks to Bruno Nicenboim for reporting this. See: https://github.com/rtdists/rtdists/issues/7
• Removed an non-used devtools:: call in tests that caused a false positive CRAN warning (June 2018).
• Deactivated a few more tests in CRAN for faster checking (June 2018).

0.7-x

Released May 2017.

• Performance of diffusion functions and rLBA increased, especially for calls with parameters that differ trialwise. As a consequence single rlba_... functions now return a matrix and no data.frame.
• All C functions are now accessed via Rcpp.
• pdiffusion uses the C++ CDF (no more numerical integration in R).
• sv can produce slow errors, and sz fast errors (this was the wrong way around in the documentation). Thanks to Gabriel Tillman for noticing that.
• Removed a bug in the pdiffusion C code letting rtdists hang indefinitely (see https://github.com/rtdists/rtdists/pull/3). Thanks to Tomas Kalibera for the fix.
• Removed bug: meanlog_v and sdlog_v were not recycled for the lnorm LBA.
• Ratcliff and Rouder (1998) vignette now uses nested data.frames and purrr::map (i.e., more proper use of the tidyverse).
• Removed bug when non-accumulator LBA parameters where passed as a named list.

0.6-6

Bug-fix version, released July 2016.

• Bug when passing start point with s != 1 removed.

0.6-x

Released July 2016.

• Start point z in diffusion model is now on absolute scale and not relative to b in line with A (start point of LBA) which is also on absolute scale. (Thanks to Steve Lewandowsky for noticing this.)
• PDFs, CDFs, and quantile functions of both models now accept a data.frame as first argument containing both RTs/probabilities and responses. Allows more convenient way to pass data.
• Renamed boundary (argument in diffusion functions) to response to be in line with LBA functions. (Thanks to Steve Lewandowsky for suggesting this.)
• Added diffusion constant s as argument to all diffusion functions.
• Added scale_p and scale_max arguments to quantile functions which automatically scale the entered probability to more conveniently obtain predicted quantiles.
• LBA functions now accept factor as response (which is converted via as.numeric). This allows to pass results from rdiffusion directly to LBA function.
• Changed integration routine in pdiffusion to pracma::integral() which seems to be more robust. (Thanks to Anna-Lena Schubert and Steve Lewandowsky for reporting problems with the previous version.)
• Removed bug preventing lnorm as distribution in rLBA. (Thanks to Steve Lewandowsky for reporting this bug.)

0.5-x

Released May 2016.

• Calculation of the CDF for the diffusion model was incorrect (this bug was present in all prior versions of rtdists). pdiffusion now simply integrates the PDF to obtain the CDF using R’s integrate which provides the correct result (albeit slower).
• Added rr98 data set: Experiment 1 from Ratcliff and Rouder (1998, Psych. Science). We thank Roger Ratcliff and Jeff Rouder for providing the data.
• Added vignette showing how to analyze the data from Ratcliff and Rouder (1998) with both diffusion and LBA model.
• Quantile functions work more robust and try uniroot if optimize does not converge.

0.4-x

Released April 2016.

• Added dLBA(), pLBA(), qLBA(), and rLBA(). dLBA() is a fully vectorized versions of n1PDF which has response as second argument, allowing to get the density for each response and corresponding response time in one step. As for the diffusion model (see below), this allows a likelihood function which only includes one call to the density function. pLBA() and qLBA() are the corresponding CDF and quantile functions, respectively. rLBA() is a fully vectorized version of the RNG functions and should be used from now on as top-level function.
• t0 in the LBA now accepts accumulator and trialwise parameters just as A and b. st0 now accepts trialwise parameter (not accumulator wise).
• Diffusion model function have been renamed to ddiffusion, pdiffusion, and rdiffusion. Added quantile function for diffusion model, qdiffusion.
• Diffusion model functions are now completely vectorized and accept vectors as parameters (including for boundary). As for the LBA, this allows a likelihood function which only includes one call to the density function (see examples).
• Boundary parameter for diffusion functions accept numeric/factor vectors.
• t0 in the diffusion model now corresponds to the lower bound of the uniform distribution from which t0 is drawn (it was the mean before). The specifications of t0 now agree between LBA and diffusion model.
• Density for diffusion model is now always positive.
• First argument in most functions (vector of response times) renamed to rt (was t before).
• PDF and CDF LBA functions more robust (now mostly return 0 instead of NaN) for problematic parameter values (such as A = 0) [2015-09-17].