Datum Calc 0.1.10

Unsaved work is safer: New, Open and an update ask first. Fixes found by an independent review of 0.1.8 and 0.1.9.

Unsaved work

• New, Open, a calc pack, a recent sheet, Getting Started and installing an update now ask “Save changes?” when the sheet has unsaved changes. Before, they replaced it without asking; only closing the window asked.
• An update writes a recovery copy of unsaved work before the window closes, so the new version offers it back (not when you chose Don't save).
• An update installs only once its checksum has been compared with SHA256SUMS.txt.
• The recovery box names the copy it offers, and Recover or Discard acts on that copy only. With two copies and two windows starting together, Discard in one window could delete a copy the other had not shown.
• A window that cannot lock its recovery copy tries another name, and a lock made in the last minute is never cleaned away, so a running window's copy never looks abandoned.
• A sheet saved under a name typed without .dcalc gets the extension, so Explorer opens it with Datum Calc; it never replaces an existing file without asking.

Results

• A torque typed with its unit (50 Nm) keeps reading in N·m in later lines (M22 = 100 N·m, not 100 J); 50 J stays an energy. A torque times an angle is work, in J.
• A unit after brackets gives a plain or complex number its unit, (8 + 6j) Ω; on a value that already has units, such as (F/A) MPa, it is an error that points to the unit menu, as before 0.1.8.
• A complex number written out (Z = (8 + 6j) Ω) is an input, so its value is not repeated; 0j is real.
• Getting Started shows torque and complex numbers.

Checks

• 54 engine tests and a shell test, 86 UI tests (Save changes? before New, a pack and a recent sheet; Cancel and Don't save). Recovery tried again in the real window with two copies and two windows. 12,000 more random sheets.

Datum Calc 0.1.9

Safer recovery when several sheets are open, two more calc packs, and smaller fixes.

Recovery

• Each Datum Calc window keeps its own recovery copy. Two sheets double-clicked in Explorer run as two windows; before, they shared one copy, and closing or saving one deleted the other's. A copy is offered again only when the window that kept it is no longer running (closed without saving, or crashed).
• Discard in the “Recover unsaved work?” box now deletes the copy; closing the box with × keeps it for next time. A copy kept by 0.1.8 is still offered.

More calc packs (19 in all)

• Heat loss from an insulated pipe: radial conduction through the insulation and the outer surface coefficient in series, the heat lost per metre and along the line, and the surface temperature for personnel protection.
• Fillet weld in shear: the simplified method for a pair of fillet welds, with the minimum throat and length.
• Each is checked against a hand calculation in the tests.

Smaller fixes

• j (or i) is drawn upright in equations when it is the imaginary unit, as in the results; a name of the sheet called j stays italic.
• A check on absolute temperatures (29.6 °C ≤ 60 °C) shows no utilisation; a ratio of kelvins meant nothing.

Checks

• 54 engine tests, 82 UI tests (Discard and × in the recovery box); 18,000 more random sheets. Recovery was tried in the real window: a crashed window's copy offered and recovered, a running window's copy never offered, Discard, a copy from 0.1.8, and two windows at once.

Datum Calc 0.1.8

What visitors asked for: complex numbers for AC circuits, and torque in N·m.

Complex numbers

• Type 4j (or 4i) for an imaginary number, and j (or i) on its own for the imaginary unit: Z = R + jomegaL. A name on the sheet called j or i takes their place; 4j stays imaginary.
• A unit after brackets applies to all of them: Z = (8 + 9.42j) Ω.
• +, −, ×, ÷ and powers work on complex values, as do sqrt, exp, ln, abs (the magnitude), sum and mean. New functions: re, im, arg (the angle), conj and polar(r, θ).
• Results show as (3 + 4j) Ω, or as magnitude and angle (5∠53.13° Ω) with View › Polar, saved with the sheet. Equations with their numbers show the complex values too.
• Checks, comparisons, solve, plots, ranges and tables work on real values and say so: compare abs(I), plot abs(Z) or arg(Z).
• New calc pack (17 in all): AC circuit, an R–L load with a capacitor in parallel for power-factor correction, with its impedance, current phasor, complex power and power factor checked against a hand calculation.

Torque

• A force times a length shows in N·m (lbf·ft in US units), and so does a power over a speed: 120 N × 0.35 m = 42 N·m, not 42 J. A power times a time still shows in J.
• N·m, kN·m, N·mm, MN·m, lbf·ft, lbf·in and kip·ft are in the unit menu of every torque and energy result.

Checks

• 52 engine tests (three new ones for complex numbers, torque and the AC pack, with the hand values first), 80 UI tests. The random-sheet test now also writes complex numbers and units after brackets; 24,000 more random sheets came through without a fault.

Datum Calc 0.1.7

• Windows now lists the publisher as Datum.

Datum Calc 0.1.6

Safer saving, three more calc packs, a summary of checks on the printed sheet, figures per sheet, Duplicate and Insert Above.

More calc packs (16 in all)

• Pipe wall thickness for internal pressure, with corrosion allowance and mill tolerance, against the nominal wall of the schedule.
• Column buckling (Euler): critical load, critical stress, slenderness, the load against the critical load with a safety factor, and whether Euler's formula applies.
• Cable voltage drop (three-phase): from resistance and reactance per km, as a percentage of the line voltage, against a limit.
• Each is checked against a hand calculation in the tests.

Printing

• Print › Summary of checks at the start: a box at the top of the first page lists every check with both values, the utilisation and PASS or FAIL, and says whether all pass. It is saved with the sheet.

Editing

• View › Figures sets how many significant figures this sheet shows (3 to 6); the engine always works at full precision.
• Duplicate (Ctrl+D) copies a region below it with its style and unit; Insert Above (Ctrl+Shift+M) adds an equation above the selected one. Both are on Home › Arrange.

Results that read better

• A check reads in the unit its value is shown in: 0.95 % ≤ 3 %, not 0.0095 ≤ 0.03.
• An input whose unit has no counterpart in the other unit system keeps its own unit (0.193 ohm/km on a US sheet). Electrical units and cP are used the same way in both systems.
• Specific energy and head on a US sheet show in BTU/lb.

Sturdier

• Saving writes to a temporary file first and then replaces the sheet in one step, so a crash or a full disk never leaves a half-written sheet.
• Files over 64 MB are refused; bytes that are not text are replaced, so a damaged sheet still opens as far as it can. Very long texts, huge pictures and oversized tables in a file are cut to the limits; an edit beyond them is refused with a message.
• If one region (or the Variables panel) ever cannot be drawn, it shows a short note and the rest of the window keeps working. A utilisation that is not a number shows nothing instead of stopping the panel.
• Every pack is saved, reopened and damaged hundreds of times in the tests; another 72,000 random sheets ran without a failure.

Datum Calc 0.1.5

A bigger release: equations shown with their numbers, three more calc packs, a list of every check, and a round of hardening that found and fixed four ways the engine could fail.

Equations with their numbers (View › Numbers)

• Each equation is shown a second time with the values put in, as on a hand calculation: P = ρ g Q H/η = 998 kg/m³ · 9.807 m/s² · 120 m³/h · 45 m / 0.75 = 19.57 kW. Each value appears in the unit it is shown in on its own line. The setting is saved with the sheet and printed.

More calc packs (13 in all)

• Shaft torsion: torque from power and speed, shear stress, the smallest diameter for an allowable stress, and the angle of twist (shown in degrees).
• Tank volume, liquid mass, bottom pressure and fill time (times of an hour or more show in hours).
• Thermal expansion of a pipe: free growth, and the stress and force if it were fully restrained, with a FAIL that shows why the line needs a loop.
• Each is checked against a hand calculation in the tests, like the first ten.

Checks

• The side panel lists every check with its utilisation and PASS or FAIL; click one to go to it.
• On a check line the badge now comes straight after the check, before its note.

Sturdier

• A line with thousands of brackets or signs inside each other could stop Datum Calc; lines are now limited (60 levels, 1,000 symbols) with a clear message, and the sheet is worked out on its own thread with plenty of room.
• A range with a tiny step (x = 0, 1e-300 .. 1) could stop Datum Calc; it now says a range holds at most 100,000 values.
• A unit power such as m^999 was quietly cut to m^127; powers of units above 60 now give a clear message.
• Results beyond about 10³⁰⁸ now say so instead of showing nothing; numbers too small to matter (below 10⁻³⁰⁰) show as 0.
• A square or cube root of a value carrying rotation (such as a torque worked out from rpm) no longer gives a units error.
• Over 100,000 random sheets (random equations, units, tables, checks, solve and plot) and 20,000 random unit strings and numbers are now worked out in the tests, in both build types, without a failure.

Smaller

• Degrees read 0.22° (no space). The Home tile counts the packs. Pasted pictures are limited to 4 MB.

Datum Calc 0.1.4

A Getting Started sheet, inputs that keep their units, clearer numbers, and calc packs that convert to US units.

Getting started

• File › Home › Getting Started (and Help › Getting Started) opens a short sheet that shows how Datum Calc works by example: inputs with units, equations and results, temperatures, a check, a function with solve and plot, and a table. Change any line and watch the rest follow.

Results

• An input keeps the unit you typed it in: I = 8356 cm^4 shows 8356 cm⁴, not 83.56×10⁶ mm⁴. In a sheet set to US units, metric inputs are shown in US units (and the other way round).
• Large numbers keep only their significant figures and are grouped in threes: a Reynolds number shows as 274 900.

Calc packs

• In a sheet set to US units, every pack result converts (psi, ksi, in, ft, gpm, hp, °F). Moments stay in kN·m, torque in N·m and apparent and reactive power in kVA and kvar, because those units cannot be told apart from energy and power automatically.

Datum Calc 0.1.3

Ten ready calc packs, notes on every line, copying results and CSV export: the convention build.

Calc packs (File › New from pack)

• Rotating equipment: pump power, efficiency and motor size; NPSH available against NPSH required; pump curve against system curve (the operating point, plotted and solved); compressor polytropic head and power.
• Process: pipe pressure drop (Darcy–Weisbach with the Colebrook friction factor solved); heat exchanger duty and LMTD.
• Mechanical: thin-walled pressure vessel (hoop and longitudinal stress, required thickness); beams (simply supported and cantilever deflection and bending stress); bolt preload and tightening torque.
• Electrical: motor full-load current, apparent and reactive power, starting current.
• Each pack has its inputs at the top (highlighted), results and checks below, and its textbook or standard at the end. Each is checked against a hand calculation in Datum Calc's tests.

Notes on a line

• Text after # describes the line and shows beside it: Q = 120 m^3/h # rated flow.

Exchange

• Right-click a region: Copy Result (19.61 kW, to paste into a spreadsheet or a report), Copy as LaTeX, Mark as Input, Move, Delete.
• File › Export › Inputs and results (CSV): every named value with its unit and whether it is an input or a result, and every check with PASS or FAIL and its utilisation.

Datum Calc 0.1.2

Tables, pictures and the list of every unit; a fix for gravity after a unit.

Tables

• Insert › Table: a small grid with a name and a unit for each column, such as a pump curve from its data sheet. Each column becomes a vector you can use below it: H_at(q) = interp(q, Q_d, H_d).
• A cell without a unit takes the column's unit; a column with a formula (rho*g*Q_d*H_d) is worked out value by value and shown in its unit.
• Double-click a table to edit it: type from cell to cell, Enter moves down (and adds a row at the bottom), + Row and + Column grow it, Done saves it as one change you can undo.

Pictures

• Insert › Picture adds a sketch or a photo, such as a free-body diagram, with a caption. Paste a picture (Ctrl+V) to add it straight away. Format › Picture sets its size.

Units, constants and functions

• Units › All Units lists every unit by kind with its name and SI units; Math › All Functions lists the functions and constants. Search, then click one to type it into the region you are editing.

Printing

• Tables and pictures print with the sheet; a region that does not fit moves to the next page instead of being cut.

Fixed

• 1000 kg/m^3*g read the g as grams; it is now gravity. The constants, a function's own parameters and the variable after for are never read as units.

Datum Calc 0.1.1

The engine arrives: every equation is worked out with its units, shown as maths, and checked.

Units

• About 200 units: SI with prefixes and US customary (m, mm, in, ft; kg, lb; N, kN, lbf, kip; Pa, kPa, MPa, bar, psi; J, kWh, BTU; W, kW, hp; m³/h, gpm, L/s; rpm, rad/s; and many more). Every factor is tested against the published NIST value.
• Write units after a number: 120 m^3/h, 2.5 kN*m, 1.2 W/(m^2*K), 9.81 m/s².
• Adding metres to seconds is an error on that line, and the wrong part of the line is underlined.
• Temperatures in °C and °F are handled correctly: 20 °C − 10 °C is a difference of 10 K, the mean of two temperatures stays a temperature, and −40 °C is −40 °F.
• Results are shown in a sensible unit (18.4 kW, 2.5 MPa, 250 mm) for the sheet's unit system (SI or US). Click ▾ after a result to show it in another unit.

Equations

• Every line is drawn as maths: fractions, roots, powers, subscripts (sigma_allow → σ with “allow” below) and Greek letters by name.
• • − × ÷, powers, brackets; sqrt, sin, cos, tan (in radians, or with deg), ln, log, exp, min, max, abs, round, if, sum, mean, interp, hypot.
• Your own functions: f(x) = 3*x^2 + 2. Ranges: x = 0, 0.1 .. 10.
• Constants: g, π, e, R, σ_SB (Stefan–Boltzmann). A name on the sheet takes the place of a constant.
• A name used before it is defined says so, and an error never stops the rest of the sheet.

Checks, solve and plot

• check sigma <= sigma_allow shows a green PASS or a red FAIL with both values and the utilisation (0.82 means 82 % used).
• solve … for x in a .. b finds the value that makes both sides equal in the range, for example the Colebrook friction factor or a pump's operating point.
• plot H_pump(Q), H_sys(Q) for Q in 0 m^3/h .. 150 m^3/h draws the curves, with a crosshair and a PNG button.

The window

• A Variables panel lists every name with its value and unit; click one to go to its line. The checks that pass and the lines with errors are counted there and in the status bar.
• The printed calc sheet shows the maths, the results and the PASS/FAIL badges.