if not modules then modules = { } end modules ['math-dim'] = {
    version   = 1.001,
    comment   = "companion to math-ini.mkiv",
    author    = "Hans Hagen, PRAGMA-ADE, Hasselt NL",
    copyright = "PRAGMA ADE / ConTeXt Development Team",
    license   = "see context related readme files"
}

-- Beware: only Taco and Ulrik really understands in depth what these dimensions
-- do so if you run into problems ask on the context list.

-- The radical_rule value is also used as a trigger. In luatex the accent
-- placement happens either the opentype way (using top_accent cum suis) or the
-- traditional way. In order to determine what method to use the \Umathradicalrule
-- setting is consulted to determine what method to use. This is more efficient
-- than analyzing the (potentially spread over multiple families) situation. For
-- this reason we need to set the radical_rule here. It used to be "<unset>" in
-- which case the engine takes the rulethickness. In c-speak:
--
-- int compat_mode = (radical_rule(cur_style) == undefined_math_parameter) ;

local abs, next = math.abs, next

local defaults = {
    axis                  = { default                     = { "AxisHeight",                               "axis_height" }, },
    accent_base_height    = { default                     = { "AccentBaseHeight",                         "x_height" }, },
    fraction_del_size     = { default                     = { "FractionDelimiterSize",                    "delim2" },
                              cramped_display_style       = { "FractionDelimiterDisplayStyleSize",        "delim1" },
                              display_style               = { "FractionDelimiterDisplayStyleSize",        "delim1" }, },
    fraction_denom_down   = { default                     = { "FractionDenominatorShiftDown",             "denom2" },
                              cramped_display_style       = { "FractionDenominatorDisplayStyleShiftDown", "denom1" },
                              display_style               = { "FractionDenominatorDisplayStyleShiftDown", "denom1" }, },
    fraction_denom_vgap   = { default                     = { "FractionDenominatorGapMin",                "default_rule_thickness" },
                              cramped_display_style       = { "FractionDenominatorDisplayStyleGapMin",    "3*default_rule_thickness" },
                              display_style               = { "FractionDenominatorDisplayStyleGapMin",    "3*default_rule_thickness" }, },
    fraction_num_up       = { default                     = { "FractionNumeratorShiftUp",                 "num2" },
                              cramped_display_style       = { "FractionNumeratorDisplayStyleShiftUp",     "num1" },
                              display_style               = { "FractionNumeratorDisplayStyleShiftUp",     "num1" }, },
    fraction_num_vgap     = { default                     = { "FractionNumeratorGapMin",                  "default_rule_thickness" },
                              cramped_display_style       = { "FractionNumeratorDisplayStyleGapMin",      "3*default_rule_thickness" },
                              display_style               = { "FractionNumeratorDisplayStyleGapMin",      "3*default_rule_thickness" }, },
    fraction_rule         = { default                     = { "FractionRuleThickness",                    "default_rule_thickness" }, },
    limit_above_bgap      = { default                     = { "UpperLimitBaselineRiseMin",                "big_op_spacing3" }, },
    limit_above_vgap      = { default                     = { "UpperLimitGapMin",                         "big_op_spacing1" }, },
    limit_above_kern      = { default                     = { "0",                                        "big_op_spacing5" }, },
    limit_below_bgap      = { default                     = { "LowerLimitBaselineDropMin",                "big_op_spacing4" }, },
    limit_below_vgap      = { default                     = { "LowerLimitGapMin",                         "big_op_spacing2" }, },
    limit_below_kern      = { default                     = { "0",                                        "big_op_spacing5" }, },
    math_operator_size    = { default                     = { "DisplayOperatorMinHeight",                 "math_x_height*3" }, }, -- 2
    overbar_kern          = { default                     = { "OverbarExtraAscender",                     "default_rule_thickness" }, },
    overbar_rule          = { default                     = { "OverbarRuleThickness",                     "default_rule_thickness" }, },
    overbar_vgap          = { default                     = { "OverbarVerticalGap",                       "3*default_rule_thickness" }, },
    quad                  = { default                     = { "font_size(f)",                             "math_quad" }, },
    radical_kern          = { default                     = { "RadicalExtraAscender",                     "default_rule_thickness" }, },
    radical_rule          = { default                     = { "RadicalRuleThickness",                     "default_rule_thickness" }, },
                           -- default                     = { "surd_height(f)",                           "default_rule_thickness" },
    radical_vgap          = { default                     = { "RadicalVerticalGap",                       "default_rule_thickness+(abs(default_rule_thickness)/4)" },
                              display_style               = { "RadicalDisplayStyleVerticalGap",           "default_rule_thickness+(abs(math_x_height)/4)" }, },
    space_after_script    = { default                     = { "SpaceAfterScript",                         "script_space" }, },
    stack_denom_down      = { default                     = { "StackBottomShiftDown",                     "denom2" },
                              cramped_display_style       = { "StackBottomDisplayStyleShiftDown",         "denom1" },
                              display_style               = { "StackBottomDisplayStyleShiftDown",         "denom1" }, },
    stack_num_up          = { default                     = { "StackTopShiftUp",                          "num3" },
                              cramped_display_style       = { "StackTopDisplayStyleShiftUp",              "num1" },
                              display_style               = { "StackTopDisplayStyleShiftUp",              "num1" }, },
    stack_vgap            = { default                     = { "StackGapMin",                              "3*default_rule_thickness" },
                              cramped_display_style       = { "StackDisplayStyleGapMin",                  "7*default_rule_thickness" },
                              display_style               = { "StackDisplayStyleGapMin",                  "7*default_rule_thickness" }, },
    sub_shift_down        = { default                     = { "SubscriptShiftDown",                       "sub1" }, },
    sub_shift_drop        = { default                     = { "SubscriptBaselineDropMin",                 "sub_drop" }, },
    sub_sup_shift_down    = { default                     = { "SubscriptShiftDown",                       "sub2" }, },
    sub_top_max           = { default                     = { "SubscriptTopMax",                          "abs(math_x_height*4)/5" }, },
    subsup_vgap           = { default                     = { "SubSuperscriptGapMin",                     "4*default_rule_thickness" }, },
    sup_bottom_min        = { default                     = { "SuperscriptBottomMin",                     "abs(math_x_height)/4" }, },
    sup_shift_drop        = { default                     = { "SuperscriptBaselineDropMax",               "sup_drop" }, },
    sup_shift_up          = { cramped_display_style       = { "SuperscriptShiftUpCramped",                "sup3" },
                              cramped_script_script_style = { "SuperscriptShiftUpCramped",                "sup3" },
                              cramped_script_style        = { "SuperscriptShiftUpCramped",                "sup3" },
                              cramped_text_style          = { "SuperscriptShiftUpCramped",                "sup3" },
                              display_style               = { "SuperscriptShiftUp",                       "sup1" },
                              script_script_style         = { "SuperscriptShiftUp",                       "sup2" },
                              script_style                = { "SuperscriptShiftUp",                       "sup2" },
                              text_style                  = { "SuperscriptShiftUp",                       "sup2" }, },
    sup_sub_bottom_max    = { default                     = { "SuperscriptBottomMaxWithSubscript",        "abs(math_x_height*4)/5" }, },
    underbar_kern         = { default                     = { "UnderbarExtraDescender",                   "0" }, },
    underbar_rule         = { default                     = { "UnderbarRuleThickness",                    "default_rule_thickness" }, },
    underbar_vgap         = { default                     = { "UnderbarVerticalGap",                      "3*default_rule_thickness" }, },
    connector_overlap_min = { default                     = { "MinConnectorOverlap",                      "0.25*default_rule_thickness" }, },
    over_delimiter_vgap   = { default                     = { "StretchStackGapBelowMin",                  "big_op_spacing1" }, },
    over_delimiter_bgap   = { default                     = { "StretchStackTopShiftUp",                   "big_op_spacing3" }, },
    under_delimiter_vgap  = { default                     = { "StretchStackGapAboveMin",                  "big_op_spacing2" }, },
    under_delimiter_bgap  = { default                     = { "StretchStackBottomShiftDown",              "big_op_spacing4" }, },
    radical_degree_before = { default                     = { "RadicalKernBeforeDegree",                  "(5/18)*quad" }, },
    radical_degree_after  = { default                     = { "RadicalKernAfterDegree",                   "(-10/18)*quad" }, },
    radical_degree_raise  = { default                     = { "RadicalDegreeBottomRaisePercent",          "60" }, },
}

local styles = {
    'cramped_display_style',
    'cramped_script_script_style',
    'cramped_script_style',
    'cramped_text_style',
    'display_style',
    'script_script_style',
    'script_style',
    'text_style',
}

for k, v in next, defaults do
    for _, s in next, styles do
        if not v[s] then
            v[s] = v.default
        end
    end
end

-- we cannot use a metatable because we do a copy (takes a bit more work)
--
-- local mt = { }  setmetatable(defaults,mt)
--
-- mt.__index = function(t,s)
--     return t.default or t.text_style or 0
-- end

function mathematics.dimensions(dimens)  -- beware, dimens get spoiled
    if dimens.SpaceAfterScript then
        dimens.SubscriptShiftDownWithSuperscript = dimens.SubscriptShiftDown * 1.5 -- move this one
        return table.fastcopy(dimens), { }
    elseif dimens.AxisHeight or dimens.axis_height then
        local t = { }
        local math_x_height = dimens.x_height or 10*65536
        local math_quad = dimens.quad or 10*65536
        local default_rule_thickness = dimens.FractionDenominatorGapMin or dimens.default_rule_thickness or 0.4*65536
        dimens["0"] = 0
        dimens["60"] = 60
        dimens["0.25*default_rule_thickness"] = default_rule_thickness / 4
        dimens["3*default_rule_thickness"] = 3 * default_rule_thickness
        dimens["4*default_rule_thickness"] = 4 * default_rule_thickness
        dimens["7*default_rule_thickness"] = 7 * default_rule_thickness
        dimens["(5/18)*quad"] = (math_quad * 5) / 18
        dimens["(-10/18)*quad"] = - (math_quad * 10) / 18
        dimens["math_x_height*3"] = math_x_height * 3 -- needs checking
        dimens["abs(math_x_height*4)/5"] = abs(math_x_height * 4) / 5
        dimens["default_rule_thickness+(abs(default_rule_thickness)/4)"] = default_rule_thickness+(abs(default_rule_thickness) / 4)
        dimens["default_rule_thickness+(abs(math_x_height)/4)"] = default_rule_thickness+(abs(math_x_height) / 4)
        dimens["abs(math_x_height)/4"] = abs(math_x_height) / 4
        dimens["abs(math_x_height*4)/5"] = abs(math_x_height * 4) / 5
        dimens["<not set>"] = false
        dimens["script_space"] = false -- at macro level
        for variable, styles in next, defaults do
            local tt = { }
            for style, default in next, styles do
                local one, two = default[1], default[2]
                local value = dimens[one]
                if value then
                    tt[style] = value
                else
                    value = dimens[two]
                    if value == false then
                        tt[style] = nil
                    else
                        tt[style] = value or 0
                    end
                end
            end
            t[variable] = tt
        end
        local d = {
            AccentBaseHeight                            = t . accent_base_height    . text_style,
            AxisHeight                                  = t . axis                  . text_style,
         -- DelimitedSubFormulaMinHeight
            DisplayOperatorMinHeight                    = t . math_operator_size    . text_style, -- no longer let tex decide (weird values)
         -- FlattenedAccentBaseHeight
            FractionDenominatorDisplayStyleGapMin       = t . fraction_denom_vgap   . display_style,
            FractionDenominatorDisplayStyleShiftDown    = t . fraction_denom_down   . display_style,
            FractionDenominatorGapMin                   = t . fraction_denom_vgap   . text_style,
            FractionDenominatorShiftDown                = t . fraction_denom_down   . text_style,
            FractionNumeratorDisplayStyleGapMin         = t . fraction_num_vgap     . display_style,
            FractionNumeratorDisplayStyleShiftUp        = t . fraction_num_up       . display_style,
            FractionNumeratorGapMin                     = t . fraction_num_vgap     . text_style,
            FractionNumeratorShiftUp                    = t . fraction_num_up       . text_style,
            FractionRuleThickness                       = t . fraction_rule         . text_style,
            FractionDelimiterSize                       = t . fraction_del_size     . text_style,
            FractionDelimiterDisplayStyleSize           = t . fraction_del_size     . display_style,
            LowerLimitBaselineDropMin                   = t . limit_below_bgap      . text_style,
            LowerLimitGapMin                            = t . limit_below_vgap      . text_style,
         -- MathLeading
            MinConnectorOverlap                         = t . connector_overlap_min . text_style,
            OverbarExtraAscender                        = t . overbar_kern          . text_style,
            OverbarRuleThickness                        = t . overbar_rule          . text_style,
            OverbarVerticalGap                          = t . overbar_vgap          . text_style,
            RadicalDisplayStyleVerticalGap              = t . radical_vgap          . display_style,
            RadicalExtraAscender                        = t . radical_kern          . text_style,
            RadicalRuleThickness                        = t . radical_rule          . text_style,
            RadicalVerticalGap                          = t . radical_vgap          . text_style,
            RadicalKernBeforeDegree                     = t . radical_degree_before . display_style,
            RadicalKernAfterDegree                      = t . radical_degree_after  . display_style,
            RadicalDegreeBottomRaisePercent             = t . radical_degree_raise  . display_style,
         -- ScriptPercentScaleDown
         -- ScriptScriptPercentScaleDown
         -- SkewedFractionHorizontalGap
         -- SkewedFractionVerticalGap
            SpaceAfterScript                            = t . space_after_script    . text_style,
            StackBottomDisplayStyleShiftDown            = t . stack_denom_down      . display_style,
            StackBottomShiftDown                        = t . stack_denom_down      . text_style,
            StackDisplayStyleGapMin                     = t . stack_vgap            . display_style,
            StackGapMin                                 = t . stack_vgap            . text_style,
            StackTopDisplayStyleShiftUp                 = t . stack_num_up          . display_style,
            StackTopShiftUp                             = t . stack_num_up          . text_style,
            StretchStackGapBelowMin                     = t . over_delimiter_vgap   . text_style,
            StretchStackTopShiftUp                      = t . over_delimiter_bgap   . text_style,
            StretchStackGapAboveMin                     = t . under_delimiter_vgap  . text_style,
            StretchStackBottomShiftDown                 = t . under_delimiter_bgap  . text_style,
            SubSuperscriptGapMin                        = t . subsup_vgap           . text_style,
            SubscriptBaselineDropMin                    = t . sub_shift_drop        . text_style,
            SubscriptShiftDown                          = t . sub_shift_down        . text_style,
            SubscriptShiftDownWithSuperscript           = t . sub_sup_shift_down    . text_style,
            SubscriptTopMax                             = t . sub_top_max           . text_style,
            SuperscriptBaselineDropMax                  = t . sup_shift_drop        . text_style,
            SuperscriptBottomMaxWithSubscript           = t . sup_sub_bottom_max    . text_style,
            SuperscriptBottomMin                        = t . sup_bottom_min        . text_style,
            SuperscriptShiftUp                          = t . sup_shift_up          . text_style,
            SuperscriptShiftUpCramped                   = t . sup_shift_up          . cramped_text_style,
            UnderbarExtraDescender                      = t . underbar_kern         . text_style,
            UnderbarRuleThickness                       = t . underbar_rule         . text_style,
            UnderbarVerticalGap                         = t . underbar_vgap         . text_style,
            UpperLimitBaselineRiseMin                   = t . limit_above_bgap      . text_style,
            UpperLimitGapMin                            = t . limit_above_vgap      . text_style,
        }

        -- too fragile for tx/px ... even the same values give different results
        d.DisplayOperatorMinHeight = nil
        --
        d.AccentBaseHeight = 0 -- here? still?
        return d, t -- t only for diagnostics
    else
        return { }, { }
    end
end

