Resources Numerical accuracy
Calculations
Every calculation under our calculation policies: what it works out, its formula and the precision it runs at. Open one to see its code as it is in the released app.
Calculations
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Section outline
The outline of a section as loops of points, centered on its bounding box.
arc point = (cx + r·cos a, cy + r·sin a), a = a₀ + (a₁ − a₀)·i ÷ n
Steel section dimensions, areas and outlines shapes/sections.js64-bit- CadCraft
- BimCraft
- DetailCraft
- PartCraft
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Rounded rectangle loop
The outer or inner loop of a rectangular hollow section with rounded corners.
Steel section dimensions, areas and outlines shapes/sections.js64-bit- CadCraft
- BimCraft
- DetailCraft
- PartCraft
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Loop area
The signed area of an outline loop.
A = ½ × Σ (xᵢ·yᵢ₊₁ − xᵢ₊₁·yᵢ)
Steel section dimensions, areas and outlines shapes/sections.js64-bit- CadCraft
- BimCraft
- DetailCraft
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Loop perimeter
The length around an outline loop.
L = Σ √(Δx² + Δy²)
Steel section dimensions, areas and outlines shapes/sections.js64-bit- CadCraft
- BimCraft
- DetailCraft
- PartCraft
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Part sizes in millimeters
The table dimensions of each size of a part family, with inch sizes converted.
mm = in × 25.4; pitch = 25.4 ÷ threads per inch
Standard parts and library items shapes/parts.js64-bit- CadCraft
- PartCraft
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Hexagon area
The area of a hexagon from its width across flats.
A = (√3 ÷ 2) × s²
Standard parts and library items shapes/parts.js64-bit- CadCraft
- PartCraft
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Mass from volume
The mass of a part in kilograms from its volume in mm³.
kg = mm³ × 10⁻⁹ × 7850, rounded to 4 decimals
Standard parts and library items shapes/parts.js64-bit- CadCraft
- PartCraft
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Inch length as a fraction
Writes an inch length as a whole number and a fraction for the part's designation.
n = round(v × 64); reduce n ÷ 64
Standard parts and library items shapes/parts.js64-bit- CadCraft
- PartCraft
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Part dimensions and mass
The full set of dimensions, the bounding box and the mass of one part.
e = 2s ÷ √3; bolt mass = (hex area × k + π ÷ 4 × d² × l) × ρ; gear: d = m·z, d_a = m(z + 2), d_f = m(z − 2.5), d_b = d·cos 20°
Standard parts and library items shapes/parts.js64-bit- CadCraft
- PartCraft
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Coordinate rounding in library items
Rounds every coordinate written into a library item's drawing.
round(v × 1000) ÷ 1000
Standard parts and library items shapes/items.js64-bit- CadCraft
- PartCraft
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Steel section as a library item
The section view or side elevation of a steel section, with its size and weight parameters.
kg/m = published mass, else area × 10⁻⁶ × 7850; weight = kg/m × length ÷ 1000
Standard parts and library items shapes/items.js64-bit- CadCraft
- PartCraft
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Bolt drawing dimensions
The head, shank, chamfer and thread lines of a bolt's side view.
thread root diameter = D − 1.22687 × pitch; chamfer = min(pitch, D ÷ 4)
Standard parts and library items shapes/items.js64-bit- CadCraft
- PartCraft
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Standard part as a library item
The drawing, size parameters and weight of a standard part as a library item.
Standard parts and library items shapes/items.js64-bit- CadCraft
- PartCraft
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Parameter levels
The evenly spaced values of a parameter between its two bounds.
vᵢ = from + (to − from) × i ÷ (steps − 1)
Design study variants and ranking study/study.js64-bit- CadCraft
- BimCraft
- DetailCraft
- PartCraft
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Rounding of parameter values
Rounds a parameter value before it is put in a variant.
v → v to 12 significant digits
Design study variants and ranking study/study.js64-bit- CadCraft
- BimCraft
- DetailCraft
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Variant list
Every combination of parameter levels, or a seeded random sample between the bounds.
random: v = from + (to − from) × u, u = 32-bit integer ÷ 2³²
Design study variants and ranking study/study.js64-bit- CadCraft
- BimCraft
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Meeting the limits
Whether a variant's results meet every limit of the study.
min goal: value ≤ limit; max goal: value ≥ limit
Design study variants and ranking study/study.js64-bit- CadCraft
- BimCraft
- DetailCraft
- PartCraft
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Trade-off front
The variants that no other variant beats on every goal at once.
a dominates b when a is no worse on every goal and better on at least one
Design study variants and ranking study/study.js64-bit- CadCraft
- BimCraft
- DetailCraft
- PartCraft
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Weighted ranking
A score for each feasible variant from its goals and the weights a person gives.
x = (value − lo) ÷ (hi − lo); score = Σ w × (x for max goals, 1 − x for min goals)
Design study variants and ranking study/study.js64-bit- CadCraft
- BimCraft
- DetailCraft
- PartCraft
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Load factor to the limit
The factor by which every load can be multiplied before the design's utilization reaches 1.
find λ with util(λ) = 1: double λ until util ≥ 1, then bisect with mid = √(lo × hi) until hi − lo ≤ 10⁻⁴ × hi
Load reserve and escape route checks study/breakit.js64-bit- CadCraft
- BimCraft
- DetailCraft
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Escape route widths
For each room, the route out whose narrowest door is widest, and its margin against the required width.
width of a route = min of its door widths; margin = width − required
Load reserve and escape route checks study/breakit.js64-bit- CadCraft
- BimCraft
- DetailCraft
- PartCraft
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Part reserve from a stress study
The load factor to first yield and to buckling of a solved part.
λ = minimum safety factor ÷ wanted safety factor; utilization = 1 ÷ λ
Load reserve and escape route checks study/breakit.js64-bit- CadCraft
- BimCraft
- DetailCraft
- PartCraft
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Matrix product
Combines two transforms into one.
o[c][r] = Σₖ a[k][r] × b[c][k]
USD transforms and placement usd/geom.js64-bit- CadCraft
- BimCraft
- ModelCraft
- TakeoffCraft
- CivilCraft
- DetailCraft
- PartCraft
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Matrix inverse
The transform that undoes another.
inverse = cofactor matrix ÷ determinant
USD transforms and placement usd/geom.js64-bit- CadCraft
- BimCraft
- ModelCraft
- TakeoffCraft
- CivilCraft
- DetailCraft
- PartCraft
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Transforming a point
Applies a transform to a point.
p′ = (M × [x, y, z, 1]) ÷ w
USD transforms and placement usd/geom.js64-bit- CadCraft
- BimCraft
- ModelCraft
- TakeoffCraft
- CivilCraft
- DetailCraft
- PartCraft
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Rotation about an axis
The matrix of a rotation by an angle in degrees about X, Y or Z.
a = deg × π ÷ 180; entries cos a, ± sin a
USD transforms and placement usd/geom.js64-bit- CadCraft
- BimCraft
- ModelCraft
- TakeoffCraft
- CivilCraft
- DetailCraft
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Quaternion to rotation matrix
The rotation matrix of an orientation stored as a quaternion.
q ÷ |q|; R₀₀ = 1 − 2(y² + z²), R₀₁ = 2(xy + wz), …
USD transforms and placement usd/geom.js64-bit- CadCraft
- BimCraft
- ModelCraft
- TakeoffCraft
- CivilCraft
- DetailCraft
- PartCraft
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Value at a time
An animated value at a given time, between its stored samples.
v = a + (b − a) × (t − t₀) ÷ (t₁ − t₀)
USD transforms and placement usd/geom.js64-bit- CadCraft
- BimCraft
- ModelCraft
- TakeoffCraft
- CivilCraft
- DetailCraft
- PartCraft
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An object's own transform
Builds the transform of one object from its list of translate, rotate, scale and matrix operations.
M = op₁ × op₂ × … in the listed order; an inverted operation uses its inverse
USD transforms and placement usd/geom.js64-bit- CadCraft
- BimCraft
- ModelCraft
- TakeoffCraft
- CivilCraft
- DetailCraft
- PartCraft
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World transform
The transform of an object in the scene, through all its parents.
W = M_root × … × M_parent × M_own
USD transforms and placement usd/geom.js64-bit- CadCraft
- BimCraft
- ModelCraft
- TakeoffCraft
- CivilCraft
- DetailCraft
- PartCraft
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Scene units and up axis
The transform from the scene's own units and up axis to meters with Z up.
scale by metersPerUnit; Y-up scenes: rotate 90° about X
USD transforms and placement usd/geom.js64-bit- CadCraft
- BimCraft
- ModelCraft
- TakeoffCraft
- CivilCraft
- DetailCraft
- PartCraft
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Placement of instanced copies
The transform of each copy of a point instancer from its position, orientation and scale.
M = translate(p) × rotate(q) × scale(s)
USD transforms and placement usd/scene.js64-bit- CadCraft
- BimCraft
- ModelCraft
- TakeoffCraft
- CivilCraft
- DetailCraft
- PartCraft
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Writing an object's transform
Stores an object's placement in the exported scene.
USD transforms and placement usd/build.js64-bit- CadCraft
- BimCraft
- ModelCraft
- TakeoffCraft
- CivilCraft
- DetailCraft
- PartCraft
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Attribute value to its storage type
Converts a list of numbers to the number type its USD attribute type calls for.
USD mesh coordinates in saved and exported files usd/build.js32-bit in part- CadCraft
- BimCraft
- ModelCraft
- TakeoffCraft
- CivilCraft
- DetailCraft
- PartCraft
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Mesh points and extent
Stores the points of a mesh and its bounding box in the scene.
extent = [min x, min y, min z, max x, max y, max z] of the points
USD mesh coordinates in saved and exported files usd/build.js32-bit in part- CadCraft
- BimCraft
- ModelCraft
- TakeoffCraft
- CivilCraft
- DetailCraft
- PartCraft
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Lamp intensity
Converts a lamp's lumens to the intensity a renderer reads.
intensity = lumens ÷ (683 × area × π)
USD mesh coordinates in saved and exported files usd/build.js32-bit, display only- CadCraft
- BimCraft
- ModelCraft
- TakeoffCraft
- CivilCraft
- DetailCraft
- PartCraft
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Single values in the binary file
Writes one number, tuple or matrix into the binary USD file.
USD mesh coordinates in saved and exported files usd/usdc-write.js64-bit- CadCraft
- BimCraft
- ModelCraft
- TakeoffCraft
- CivilCraft
- DetailCraft
- PartCraft
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Arrays in the binary file
Writes an array of numbers into the binary USD file.
USD mesh coordinates in saved and exported files usd/usdc-write.js32-bit in part- CadCraft
- BimCraft
- ModelCraft
- TakeoffCraft
- CivilCraft
- DetailCraft
- PartCraft
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Reading a mesh
The points, faces and attached values of a mesh read from a USD scene.
USD mesh coordinates in saved and exported files usd/geom.js32-bit in part- CadCraft
- BimCraft
- ModelCraft
- TakeoffCraft
- CivilCraft
- DetailCraft
- PartCraft
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Built-in shapes as meshes
A cube, sphere, cylinder, cone, capsule or plane of a USD scene as a mesh.
ring point = (r·cos θ, r·sin θ, z), θ = 2π·j ÷ 24
USD mesh coordinates in saved and exported files usd/geom.js64-bit- CadCraft
- BimCraft
- ModelCraft
- TakeoffCraft
- CivilCraft
- DetailCraft
- PartCraft
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Parameter values in dependency order
Evaluates every parameter after the ones it uses and reports cycles and missing values.
Parameters and equations params.js64-bit- CadCraft
- PartCraft
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Equation results written to their targets
Evaluates each equation and writes the result into the dimension or feature value it drives.
written when |current − v| > 1e-12 × max(1, |v|)
Parameters and equations params.js64-bit- CadCraft
- PartCraft
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Limits on a driven value
Checks a value against its target's kind: whole number, minimum, maximum.
Parameters and equations params.js64-bit- CadCraft
- PartCraft
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Backward solve for a driving parameter
Finds the parameter value that makes an equation give the value a person typed.
secant: c = b − f(b) × (b − a) ÷ (f(b) − f(a)); stop when |f| ≤ 1e-10 × max(1, |target|, |x₀|)
Parameters and equations params.js64-bit- CadCraft
- PartCraft
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Rounding of the solved value
Replaces the solved value by the roundest number near it that still solves the equation.
first of round(x, d decimals) for d = 0…10, then x to 12 significant digits, that keeps |f| within tolerance; else x
Parameters and equations params.js64-bit- CadCraft
- PartCraft
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Edited dimension written back to a parameter
When a driven value is edited, changes the driving parameter behind its equation, or rewrites a constant equation to the new number.
Parameters and equations params.js64-bit- CadCraft
- PartCraft
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Value typed for a parameter
Sets a driving parameter to a typed value, or solves the driving parameter behind a driven one.
Parameters and equations params.js64-bit- CadCraft
- PartCraft
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Removing a parameter and writing its value in
Removes a parameter and, when asked, writes its current value into every expression that used it.
Parameters and equations params.js64-bit- CadCraft
- PartCraft
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Design table row made permanent
Writes a set of override values into the parameters.
Parameters and equations params.js64-bit- CadCraft
- PartCraft
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Face-frame default sizes
The stile and rail width, overlay and door gap a job uses when it sets none.
stile = rail = 38 mm; overlay = 12 mm; gap = 3 mm; inch job: round(mm ÷ 25.4 × 16) ÷ 16
CabinetCraft parts, fronts and face frames addons/cabinetcraft/lib/build.js64-bit- CadCraft
- BimCraft
- ModelCraft
- PartCraft
A calculation is added only after its source was read. Each statement can be checked in the code shown on its policy's page; the app repositories are public. When a release changes a calculation, its page says so until it has been read again.