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Create a decimal arithmetic context

Source: R/context.R
decimal_context.Rd

Constructs a validated arithmetic context for native mpdecimal operations. The context controls precision, rounding, exponent limits, traps, sticky flags, and classification of normal versus subnormal values.

Usage

decimal_context(
  precision = 28L,
  rounding = "half_even",
  emax = 999999L,
  emin = -999999L,
  traps = decimal_default_traps(),
  flags = character(),
  clamp = FALSE
)

Arguments

precision

Integer scalar precision.

rounding

One of "up", "down", "ceiling", "floor", "half_up", "half_down", "half_even", or "05up".

emax

Integer scalar maximum exponent.

emin

Integer scalar minimum exponent.

traps

Character vector of trapped signals. Trapped signals raise an error; all other raised signals are recorded as flags and, unless options(decimal.report_flags = FALSE), reported as warnings.

flags

Character vector of sticky signal flags.

clamp

Logical scalar clamp mode.

Value

A decimal_context object.

Details

Each operation may raise one or more signals (see decimal_flags()). Their disposition depends on traps:

  • A raised signal that is in traps stops the operation with an error.

  • Any other raised signal is recorded as a sticky flag and, by default, also surfaced as a warning of class decimal_flags_warning.

The warnings are purely informational; sticky flags accumulate either way. Set options(decimal.report_flags = FALSE) to silence them and rely on decimal_flags() alone.

Public signal names are "clamped", "division_by_zero", "inexact", "invalid_operation", "overflow", "rounded", "subnormal", and "underflow". The standard invalid_operation condition groups lower-level invalid subconditions such as undefined division (0 / 0).

A few operations are exempt from the warning because inexact/rounded is their guaranteed, expected outcome rather than a surprise: quantize() (and round()/signif(), built on it), and sqrt(), exp(), log(), and log10(), which are irrational for nearly every input. These still accumulate sticky flags as usual.

Examples

decimal_context(precision = 10L)
#> <decimal_context>
#>   precision: 10
#>   rounding:  half_even
#>   emin:      -999999
#>   emax:      999999
#>   clamp:     FALSE
#>   traps:     [division_by_zero, invalid_operation, overflow]
#>   flags:     []
decimal_context(precision = 3L, rounding = "floor", traps = character())
#> <decimal_context>
#>   precision: 3
#>   rounding:  floor
#>   emin:      -999999
#>   emax:      999999
#>   clamp:     FALSE
#>   traps:     []
#>   flags:     []