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 view
Draws the model in 3D and finds the part under the pointer.
- DetailCraft
- 3 calculations
32-bit, display only -
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 -
Analytical frame model from the drawn members
Turns the drawn beams, columns and braces into the nodes, members, sections, supports and loads the frame solver works on.
- DetailCraft
- 8 calculations
64-bit -
Arithmetic on typed lengths
Works out a length typed as an expression, such as 4+7/16 or 2*450mm, wherever a length is asked for.
- CadCraft
- ModelCraft
- MarkupCraft
- TakeoffCraft
- CivilCraft
- DetailCraft
- 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 -
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 -
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 between parts
Finds steel parts and footings that run into each other and reports how deep and where.
- DetailCraft
- 9 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 -
Connection autopilot starting sizes
Proposes a connection for every joint that has none: bolt size and count, plate sizes and rod spacing, from the shapes and an optional end shear.
- DetailCraft
- 6 calculations
64-bit Open item -
Connection plates, holes, bolts and cut-backs
Works out where each connection's plates, holes, bolts and welds go and how far the joined members are cut back, from the connection's parameters.
- DetailCraft
- 24 calculations
64-bit Open item -
Constructability checks
Warns about bolts a socket cannot reach, bolts too close for a socket, fillet welds outside size limits, welds a torch cannot reach, and tubes that hold water.
- DetailCraft
- 6 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 -
Cut-list nesting of bars
Nests the linear parts of a model on stock bars and reports the bars to buy, the length bought and used, the drop of each bar and the waste.
- BimCraft
- DetailCraft
- 3 calculations
64-bit -
Design study variants and ranking
Makes the list of variants a design study runs, checks each result against its limits, finds the trade-off front and ranks the variants.
- CadCraft
- BimCraft
- DetailCraft
- PartCraft
- 6 calculations
64-bit Open item -
Device number check
The check on the accuracy page that reports how many bits this device's numbers carry, how many processor threads and how much memory the browser shows, and what it says about the graphics processor.
Every app 64-bit, direct- 2 calculations
64-bit -
Dimensions and views on drawing sheets
Lays out plans, elevations, assembly drawings and anchor plans, and works out the dimension figures, scales and hidden lines printed on them.
- DetailCraft
- 13 calculations
64-bit Open item -
Drawing sheets as DWG and DXF
Writes a drawing sheet's lines, circles, fills and text into a DWG model or a DXF R12 file at 1 unit = 1 mm on paper.
- DetailCraft
- 6 calculations
64-bit -
DSTV NC files
Writes one NC file per part mark for the shop's machines: the header, the outer contours and the holes.
- DetailCraft
- 8 calculations
64-bit -
DWG object values written and read
Carries the coordinates, angles, widths and scales of drawing objects between the drawing and the DWG file's object records.
- CadCraft
- BimCraft
- ModelCraft
- TakeoffCraft
- CivilCraft
- DetailCraft
- PartCraft
- 15 calculations in 3 files
64-bit Open item -
Erection movie player
Draws the erection sequence as a moving 3D picture in the exported movie page.
- DetailCraft
- 2 calculations
32-bit, display only -
Erection plan: picks, crane loads and times
Works out what the crane lifts, each pick's weight, radius, share of the load chart, hook height and time.
- DetailCraft
- 10 calculations
64-bit Open item -
Fault trees and reliability block diagrams
The probability of a top event, minimal cut sets, importance measures, system reliability and mean time to failure.
Every app 64-bit, stated limit- 10 calculations
64-bit Open item -
Finding joints between members
Finds where a beam end meets a column, where two members meet end to end in line or at an angle, and where a brace lands on another member.
- DetailCraft
- 5 calculations
64-bit -
Floats read from USD files
Reads numbers from .usda and .usdc files, in the type each value is stored as.
- CadCraft
- BimCraft
- ModelCraft
- TakeoffCraft
- CivilCraft
- DetailCraft
- PartCraft
- 5 calculations in 2 files
32-bit in part Open item -
Flow simulation (discrete events)
Queues, servers, conveyors, vehicles and resources simulated event by event: utilization, waiting times, throughput and their confidence ranges.
Every app 64-bit, stated limit- 15 calculations in 2 files
64-bit Open item -
Footing design checks
Checks a footing for bearing, sliding, overturning, bending, shear, punching, bar development and depth from the column loads and the soil you describe.
- DetailCraft
- 18 calculations
64-bit Open item -
Forces and deflection along a member
The axial force, shears, torque, bending moments and deflected shape along each member, and the largest values the report and the design checks read.
- CadCraft
- BimCraft
- DetailCraft
- 4 calculations
64-bit Open item -
Frame analysis with slabs, walls and rigid floors
Solves a frame that has plates and rigid floor diaphragms, and works out plate results at nodes and the drift of each story.
- CadCraft
- BimCraft
- DetailCraft
- 12 calculations
64-bit Open item -
Frame analysis: loads, releases, end forces and reactions
Turns loads into nodal forces, takes released ends out of each member, and works out member end forces, support reactions and the load and reaction totals of a solved frame.
- CadCraft
- BimCraft
- DetailCraft
- 13 calculations
64-bit -
Framing panels and cut lists
Lays out the studs, plates, headers, joists and rafters of a framing panel, lists the pieces to cut, and places them in the model as members.
- BimCraft
- DetailCraft
- 12 calculations
64-bit Open item -
GDSII layout: reals, flattening, areas and checks
Reading and writing chip layout streams, flattening cell hierarchies, layer areas and the basic width, spacing and area checks.
Every app 64-bit, stated limit- 12 calculations
64-bit Open item -
Gerber and drill file numbers
The coordinates and sizes written to Gerber layers, drill files and the job file, and read back from them.
Every app 64-bit, stated limit- 7 calculations
64-bit Open item -
Half floats in USD
Converts between 16-bit half floats and 32-bit floats for USD half types.
- CadCraft
- BimCraft
- ModelCraft
- TakeoffCraft
- CivilCraft
- DetailCraft
- PartCraft
- 2 calculations
32-bit in part Open item -
IFC 4.3 infrastructure quantities and files
Reads the quantities, stations and alignment lengths of roads, railways, bridges and other infrastructure from an IFC file, totals them per class, and writes a new IFC 4.3 file.
- BimCraft
- TakeoffCraft
- CivilCraft
- DetailCraft
- 9 calculations
64-bit Open item -
IFC alignment curves and stations
Reads the alignment curves of an IFC 4.3 file as sampled 3D polylines, finds the point at a station, places elements along them and builds solids swept between cross sections.
- BimCraft
- TakeoffCraft
- CivilCraft
- DetailCraft
- 7 calculations
64-bit Open item -
IFC curves and profiles as point lists
Turns the curves and cross-section profiles of an IFC file into polylines: arcs, circles, ellipses, trimmed curves, B-splines, offsets, and the standard steel shapes with their fillets.
- BimCraft
- TakeoffCraft
- CivilCraft
- DetailCraft
- 10 calculations in 2 files
64-bit Open item -
IFC export
Writes the steel parts, holes, copes, mitre cuts, bolts, footings, bars and grids of the model as an IFC4 file.
- DetailCraft
- 10 calculations
64-bit Open item -
IFC faces on curved surfaces
Tessellates faces that lie on cylinders, cones, spheres, tori, swept surfaces and B-spline surfaces into triangles.
- BimCraft
- TakeoffCraft
- CivilCraft
- DetailCraft
- 11 calculations
64-bit -
IFC geometry handed to the apps
Gives each app an element's triangles and the matrix that places them, in meters with Y up, moved near the origin.
- BimCraft
- TakeoffCraft
- CivilCraft
- DetailCraft
- 4 calculations
32-bit in part Open item -
IFC import
Turns the steel members, plates, holes, copes, bolts, grids and levels of an IFC file into a DetailCraft model.
- DetailCraft
- 14 calculations
64-bit Open item -
IFC measures in SI for USD
Converts IFC lengths, areas and volumes to meters, square meters and cubic meters when properties are written to USD.
- CadCraft
- BimCraft
- ModelCraft
- TakeoffCraft
- CivilCraft
- DetailCraft
- PartCraft
- 1 calculation
64-bit -
IFC openings, clippings and half-space cuts
Cuts openings and clipping solids out of an IFC element's mesh, so the element is drawn and measured with its voids.
- BimCraft
- TakeoffCraft
- CivilCraft
- DetailCraft
- 8 calculations
32-bit in part Open item -
IFC swept solids, primitives and faceted shapes
Builds the meshes of extruded, revolved and swept solids, swept disks such as rebar and pipes, the basic primitives, and faceted boundary shapes.
- BimCraft
- TakeoffCraft
- CivilCraft
- DetailCraft
- 10 calculations in 2 files
64-bit
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.