Resources
Numerical accuracy
The calculations in our apps: the policy each one is under, the precision it runs at, and the code itself.
Calculation policies
A policy says how one family of calculations keeps its precision. Open one to see its calculations, by source file, and their code.
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3D frame analysis
Member forces, reactions and deflections of a 3D frame by the direct stiffness method.
- CadCraft
- BimCraft
- DetailCraft
- 4 calculations
64-bit -
3D vectors, planes and transforms
The vector, plane, ray and 4×4 matrix helpers that the 3D modeling kernel uses for every point it stores.
- CadCraft
- BimCraft
- ModelCraft
- TakeoffCraft
- CivilCraft
- 12 calculations
64-bit Open item -
3D view drawing
Draws the model in the 3D view: section planes and boxes, the turned section frame, picking and walking.
- BimCraft
- 3 calculations
32-bit, display only -
4D schedule dates and status
Reads task dates from a schedule file and says, for a date, which elements are built, in progress or not started.
- BimCraft
- 3 calculations
Exact -
Activated sludge plant steady state (ASM1)
Works out the steady concentrations in a chain of treatment tanks with recycles and a clarifier, the effluent and waste sludge, the sludge age and the mass balances.
- CadCraft
- BimCraft
- 8 calculations
64-bit Open item -
Activity coefficients and Henry's law
Works out liquid activity coefficients by NRTL, Wilson and UNIQUAC and Henry's constants for dissolved gases.
- CadCraft
- BimCraft
- 6 calculations
64-bit -
Analysis results drawn on the model
The deflected shape, force diagrams and colored plate contours shown on the 3D view.
- CadCraft
- BimCraft
- DetailCraft
- 3 calculations in 2 files
32-bit, display only -
Animation keys, curves and poses
Where the camera and every moving object are at a given time of an animation, and the value of every animated property.
- BimCraft
- ModelCraft
- PartCraft
- 23 calculations
64-bit -
AR on site: lining the model up with the building
Fits the model to the real site from two reference points pointed at with a phone, and checks that fit on a later visit.
- BimCraft
- ModelCraft
- 4 calculations in 2 files
64-bit -
Asset service life and maintenance due dates
Stores an asset's service life in the IFC file and reads it back in years, and marks maintenance as overdue or due soon from its next date.
- BimCraft
- 4 calculations
64-bit -
Assistant answers: fire ratings and room areas
Answers two questions a connected assistant asks of the open model: which walls have a given fire rating, and which rooms are under or over a given area.
- BimCraft
- 3 calculations
64-bit -
Assistant answers: what is above an element
Lists the elements whose bounding box starts within a distance above an element's top and overlaps its footprint, nearest first, with the gap in meters.
- BimCraft
- 1 calculation
32-bit in part Open item -
Automatic plan dimensions
Chooses the points an automatic row of dimensions measures between: the building's overall size and the stops along each outside edge.
- BimCraft
- 6 calculations
64-bit Open item -
Average daylight factor of rooms
Works out each room's average daylight factor from its windows, its inside surfaces and the angle of sky each window sees.
- BimCraft
- 13 calculations
64-bit -
Batch schedule and batch inventory
Places a recipe's steps on the plant's vessels for a number of batches and reports start and finish hours, utilization, cycle time and batches per day; keeps a mole inventory of charges, transfers, reactions and discharges.
- CadCraft
- BimCraft
- 4 calculations
64-bit -
Board geometry and clearances
Distances between tracks, pads and zones, point-in-shape tests, areas and pad positions on a printed circuit board.
Every app 64-bit, direct- 10 calculations in 2 files
64-bit Open item -
Board placement and routing
Where parts are placed and where tracks and vias run on a board, with the wire length reported.
Every app 64-bit, stated limit- 8 calculations in 2 files
64-bit Open item -
Building data for flood, wind and earthquake checks
Takes room floor heights, opening sills, storey heights, areas, widths and masses from the model for the hazard checks.
- BimCraft
- 3 calculations
64-bit -
Cabinet job cost estimate
Prices a cabinet job from its sheets, edge banding, frame stock, hardware, countertops, labor and machine time, with markup and tax.
- CadCraft
- BimCraft
- ModelCraft
- PartCraft
- 10 calculations
64-bit Open item -
Cabinet job edits that change sizes
Works out the sizes an edit puts into a cabinet job: the job in the other unit, a filler for a leftover, a gap at a door or window, and the notch of a new L or U room.
- CadCraft
- BimCraft
- ModelCraft
- PartCraft
- 4 calculations
64-bit Open item -
Cabinet job totals: linear stock and sheet count
Adds up the hardwood to buy by length and counts the sheets a nested job uses.
- CadCraft
- BimCraft
- ModelCraft
- PartCraft
- 2 calculations
64-bit -
Cabinet material sizes, grooves and drill files
Holds the thicknesses of the sheet materials and edge bands, derives the groove and sheet size from the picks, and writes the drill and G-code files.
- CadCraft
- BimCraft
- ModelCraft
- PartCraft
- 5 calculations in 2 files
64-bit -
Cabinet parts from a box and construction rules
Turns a cabinet's width, height and depth and the shop's construction rules into the parts to cut: sides, bottom, top or rails, back, shelves, doors, drawer fronts and drawer boxes.
- CadCraft
- BimCraft
- ModelCraft
- PartCraft
- 6 calculations
64-bit -
Cabinet plan, elevation, section and 3D boxes
Builds the drawing geometry of a cabinet job: each cabinet in plan, front view and section, the dimensioned shop drawings, and the boxes of the 3D view.
- CadCraft
- BimCraft
- ModelCraft
- PartCraft
- 13 calculations in 3 files
64-bit Open item -
Cabinet run layout and countertops
Places every cabinet, filler and end panel along its wall or island, works out how runs meet at corners, and sizes the countertops.
- CadCraft
- BimCraft
- ModelCraft
- PartCraft
- 19 calculations in 2 files
64-bit Open item -
Cabinet shop drawings as drawing objects
Turns the cabinet plan, elevations, sections, schedule, cut list and nested sheets into lines, polylines, texts, hatches and dimensions of the open drawing (CabinetCraft add-on).
- CadCraft
- BimCraft
- ModelCraft
- PartCraft
- 6 calculations
64-bit Open item -
CabinetCraft parts, fronts and face frames
Works out the cut-list parts of a cabinet job: face-frame stiles and rails, overlay doors and drawer fronts, drawer boxes, blind panels, fillers and end panels.
- CadCraft
- BimCraft
- ModelCraft
- PartCraft
- 11 calculations
64-bit Open item -
CabinetCraft room picking and dry-run units
Snaps picked room corners to a grid, decides which way round the picked outline runs, and converts sheet sizes between the job's units and a G-code program's units for the dry run.
- CadCraft
- BimCraft
- ModelCraft
- PartCraft
- 4 calculations
64-bit Open item -
Cabinets as 3D viewport bodies
Turns the cabinet job into boxes and meshes for the 3D viewport: every panel, the floor and the walls with their openings (CabinetCraft add-on).
- CadCraft
- BimCraft
- ModelCraft
- PartCraft
- 2 calculations
32-bit, display only -
Cabinets on angled and curved walls
The geometry of cabinets on walls that are not at right angles or are curved: arc walls from radius, sweep or three points, cabinets stepped round an arc, and the corner cabinet at any angle (CabinetCraft add-on).
- CadCraft
- BimCraft
- ModelCraft
- PartCraft
- 16 calculations
64-bit Open item -
Calc sheet units, functions and driven parameters
The unit factors, powers, functions and conversions of a calc sheet, and the values a sheet writes into the app's parameters.
Every app 64-bit, direct- 13 calculations
64-bit Open item -
Calc sheets
Unit-aware formulas saved with the file: spans, loads, moments, pass or fail checks.
Every app 64-bit, direct- 3 calculations
64-bit Open item -
Calculator results and export
Turns what a process calculator works out into the lines of its results table, its CSV export and the one figure it gives the status bar.
- CadCraft
- BimCraft
- 7 calculations in 2 files
64-bit Open item -
Camera exposure and white balance
The exposure value shown in the render dialog, the exposure in stops, and the color gains for a white-balance temperature.
- BimCraft
- ModelCraft
- 4 calculations
64-bit -
Capital and operating cost
Estimates the purchased and installed cost of process equipment and the yearly cost of its energy.
- CadCraft
- BimCraft
- 5 calculations
64-bit -
Check report values
The required and found values written in the Problems panel and in the check report exported as CSV.
Every app 64-bit, direct- 1 calculation
64-bit Open item -
Circuit solver
Operating point, DC sweep, AC response and transient of a circuit of resistors, capacitors, inductors, sources, diodes, transistors and switches.
Every app 64-bit, stated limit- 18 calculations in 2 files
64-bit Open item -
Clash check
Finds pairs of elements whose surfaces run into each other and reports how deep their boxes overlap.
- BimCraft
- 5 calculations
32-bit in part Open item -
COBie export: sizes, areas and durations
Writes floor elevations and heights, room heights and areas, warranty durations and expected life into the COBie workbook, and reads service life and warranty back from one.
- BimCraft
- 6 calculations
64-bit -
Columns: height and quantities
Works out a column's height from its levels and the length, cross-section area and volume written with it.
- BimCraft
- 4 calculations
64-bit -
Concrete member and slab checks on a solved frame
Checks every concrete beam and column of a solved frame for every strength combination, magnifies the moments of slender columns, and sizes a slab's reinforcement from the plate moments.
- CadCraft
- BimCraft
- DetailCraft
- 11 calculations in 3 files
64-bit -
Concrete member strength to ACI 318-19
The design strengths of a rectangular reinforced concrete section in bending, shear and combined axial force and bending.
- CadCraft
- BimCraft
- DetailCraft
- 9 calculations
64-bit Open item -
Concrete section by strain compatibility
The axial force and moment a rectangular reinforced concrete section carries for a given neutral axis depth, and the depth that balances a given axial force.
- CadCraft
- BimCraft
- DetailCraft
- 5 calculations
64-bit -
Conduit and tray fill, cable schedule
Works out how full a conduit or cable tray is, picks the smallest conduit that holds a set of cables, routes cables through the carriers and lists their lengths.
- CadCraft
- BimCraft
- 8 calculations
64-bit Open item -
Construction schedule dates and critical path
Reads and writes a project schedule, and works out each task's earliest and latest dates, its float and the critical path.
- BimCraft
- 5 calculations
64-bit -
Controller standard functions and integer types
Timers, counters, arithmetic functions and type conversions of the soft controller.
Every app 64-bit, direct- 6 calculations
64-bit Open item -
Coordinate readouts and survey point
Says where a point is: its distance from the project origin, the level it is on, its height above that level and its map grid coordinates.
- BimCraft
- 8 calculations
64-bit -
Coordinate reference systems
Converts project coordinates to and from a named map projection, longitude and latitude, and other systems, and reports grid scale factor, convergence and elevation factor at a point.
- CadCraft
- BimCraft
- CivilCraft
- 17 calculations in 2 files
64-bit -
Corner cabinet drilling positions
Works out where the shelf-pin, hinge-plate, fixing, pivot and shaft holes go on the parts of a corner cabinet.
- CadCraft
- BimCraft
- ModelCraft
- PartCraft
- 7 calculations
64-bit Open item -
Corner cabinets: parts and solids
Builds the cut list, door sizes, hardware counts and 3D solids of L-shaped, diagonal and lazy-susan corner cabinets (CabinetCraft add-on).
- CadCraft
- BimCraft
- ModelCraft
- PartCraft
- 11 calculations
64-bit Open item
A policy is added only after its source was read. Each statement can be checked in the code shown on its page; the app repositories are public. When a release changes a calculation, its page says so until it has been read again.
The standard
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64-bit everywhere
Every calculation runs in 64-bit floating point (IEEE 754 double precision), from the number you type to the number you read.
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15 digits, always
A 64-bit number keeps any 15-digit value intact and takes 17 digits to write out in full. Our rule for every calculation: carry all 17 between steps, and order the arithmetic so that avoidable rounding never costs one of the first 15.
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32-bit gets a warning
A 32-bit number keeps about 7 digits. Where a 32-bit step can reach a number you read, the calculation is flagged in the lists below, and the app will warn that the result can have less mathematical precision.
This device
What this browser can see of your machine. It is shown here only and sent nowhere; the desktop app reads the full hardware, a web page cannot.
The apps calculate in 64-bit on every device. Work handed to the graphics processor is the exception: browsers expose graphics processors as 32-bit calculators, which can provide less mathematical precision.
- Processor
- Memory
- Numbers in the apps
- Graphics processor (WebGL)
- WebGPU
A browser reports a rounded or capped view of the machine, never a full inventory: it gives the number of processor threads (not the model), memory rounded down and capped at 8 GB (Chromium only), and one graphics adapter even when a machine has several. What the browser reports about graphics is a capability, not a measurement of the card. The size of a graphics card's memory bus (a 192-bit bus, for example) says how fast data moves, not how precisely it calculates. Most graphics cards can calculate in 64-bit natively, slowly, but WebGL and WebGPU do not offer it to web pages.
Approaches
Every policy takes one of five approaches to keeping its precision.
- Exact values 8 policies
- Constants and factors are held as exact fractions from their definitions. The arithmetic is ordered so that no rounded factor is ever used.
- Exact predicates 1 policy
- Coordinates are 64-bit. The yes-or-no decisions that shape the geometry (which side of a line, inside or outside a circle) are computed exactly, so rounding cannot flip one.
- 64-bit, direct 337 policies
- Every value is a 64-bit number from input to result. Formulas are closed form or a direct solve, and every comparison uses a stated tolerance.
- 64-bit, stated limit 428 policies
- The arithmetic is 64-bit, but the method or the data sets the accuracy: a solver tolerance, a mesh, a step size, a datum shift, a table. The limit is stated where the result is shown.
- Display only 49 policies
- Computed to draw the screen, often in 32-bit on the graphics processor. No number a person reads, saves or exports comes from it.
- 32-bit step, flagged 118 policies
- One step stores or exchanges 32-bit values that reach a number a person reads. It is listed here with its open item, and the step is either moved to 64-bit or the app will warn where the number is read.
Precision is not robustness
Mathematical precision is how many digits a number keeps. Geometric robustness is whether a shape stays valid: every intersection found, every solid closed, every face joined to its neighbors. They are different properties, and a CAD system can have the first without the second.
Every geometric algorithm rests on yes-or-no questions. Is this point left or right of that line? Do these two edges cross? Is this point inside that circle? Each answer is the sign of a small expression. When three points are almost in line, the true value of that expression can be smaller than the rounding error of the arithmetic that computes it, and the sign comes out wrong. That happens at 15 digits as readily as at 7.
One wrong sign is not a small error in the last digit. It is a different decision: an intersection that is missed, two triangles that overlap, a face that points the wrong way, a solid with a gap in it. Every coordinate can be correct to 15 digits while the shape they describe is invalid.
What makes geometry robust
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Exact predicates
The yes-or-no questions are answered exactly. The fast 64-bit answer is used when it is safely away from zero. When it is not, the sign is computed again with as many digits as it takes.
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Decide once
A decision about a shape is recorded as topology, and every later step agrees with it. The same question is never asked twice with a chance of two answers.
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Stated tolerances
Where a tolerance is used it is written down, scaled to the size of the geometry and applied the same way everywhere.
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Local origins
Coordinates far from zero are moved to a local origin before the work, so the digits are spent on the geometry and not on the distance to the origin.
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Valid by construction
Algorithms whose result is guaranteed to be a closed solid, whatever the input, in place of ones that repair the result afterwards.
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More than the language
These choices matter more than the programming language. JavaScript, C++ and Rust all compute with the same 64-bit numbers: the same algorithm is as robust, or as fragile, in each.
Where our apps stand
The list on this page records both properties. Surface triangulation in CivilCraft and BimCraft uses exact predicates. Solid modeling in PartCraft runs on a kernel whose result is a closed solid by construction. The intersections in the CadCraft app use stated tolerances today, and exact tests for the near-parallel and near-tangent cases are an open item. Each policy says which approach it takes.