R/airy_functions.R

In boostmath: 'R' Bindings for the 'Boost' Math Functions

#' @title Airy Functions
#' @description Functions to compute the Airy functions Ai and Bi, their derivatives, and their zeros.
#' @name airy_functions
#' @param x Input numeric value
#' @param m The index of the zero to find (1-based).
#' @param start_index The starting index for the zeros (1-based).
#' @param number_of_zeros The number of zeros to find.
#' @return Single numeric value for the Airy functions and their derivatives, or a vector of length `number_of_zeros` for the multiple zero functions.
#' @seealso [Boost Documentation](https://www.boost.org/doc/libs/latest/libs/math/doc/html/math_toolkit/airy.html) for more details on the mathematical background.
#' @examples
#' airy_ai(2)
#' airy_bi(2)
#' airy_ai_prime(2)
#' airy_bi_prime(2)
#' airy_ai_zero(1)
#' airy_bi_zero(1)
#' airy_ai_zero(start_index = 1, number_of_zeros = 5)
#' airy_bi_zero(start_index = 1, number_of_zeros = 5)
NULL

#' @rdname airy_functions
#' @export
airy_ai <- function(x) {
  .Call(`airy_ai_`, x)
}

#' @rdname airy_functions
#' @export
airy_bi <- function(x) {
  .Call(`airy_bi_`, x)
}

#' @rdname airy_functions
#' @export
airy_ai_prime <- function(x) {
  .Call(`airy_ai_prime_`, x)
}

#' @rdname airy_functions
#' @export
airy_bi_prime <- function(x) {
  .Call(`airy_bi_prime_`, x)
}

#' @rdname airy_functions
#' @export
airy_ai_zero <- function(m = NULL, start_index = NULL, number_of_zeros = NULL) {
  if (!is.null(m)) {
    if (!is.null(start_index) && !is.null(number_of_zeros)) {
      stop("Please provide either 'm' or 'start_index' and 'number_of_zeros', not both.",
          call. = FALSE)
    }
    return(.Call(`airy_ai_zero_`, m))
  }

  if (is.null(start_index) || is.null(number_of_zeros)) {
    stop("Both 'start_index' and 'number_of_zeros' must be provided when 'm' is NULL.",
         call. = FALSE)
  }
  .Call(`airy_ai_zero_multiple_`, start_index, number_of_zeros)
}

#' @rdname airy_functions
#' @export
airy_bi_zero <- function(m = NULL, start_index = NULL, number_of_zeros = NULL) {
  if (!is.null(m)) {
    if (!is.null(start_index) && !is.null(number_of_zeros)) {
      stop("Please provide either 'm' or 'start_index' and 'number_of_zeros', not both.",
          call. = FALSE)
    }
    return(.Call(`airy_bi_zero_`, m))
  }

  if (is.null(start_index) || is.null(number_of_zeros)) {
    stop("Both 'start_index' and 'number_of_zeros' must be provided when 'm' is NULL.",
         call. = FALSE)
  }
  .Call(`airy_bi_zero_multiple_`, start_index, number_of_zeros)
}