Quantities, units and notes

A quantity line defines a name:

name: expression [-> unit] [| note]
name = expression
a: 1; b: 2 | note for b

The colon and the equals sign both work. The result shows what an equation line shows in Calcpad: the name, the formula, the numbers put in, and the answer with its unit.

Names

A name is made of letters, digits, _ and primes. Greek spellings become Greek letters:

phi: 0.9
sigma_c: 25 MPa
Delta_T: 40 K
phiMs: phi * 369 kN*m
Mstar: 54 kN*m

φ = 0.9
σ_c = 25 MPa
Δ_T = 40 K
φMs = φ · 369 kN·m = 0.9 · 369 kN·m = 332.1 kN·m
M_star = 54 kN·m

phi is φ, sigma_c is σ with a subscript c, Delta_T is Δ with a subscript T.
A Greek spelling followed by a capital or a digit (phiMs, sigma2) is the letter and the rest.
Capital Greek letters are written only where they differ from a Latin capital: Gamma, Delta, Theta, Lambda, Xi, Pi, Sigma, Upsilon, Phi, Psi, Omega.
A name that ends in star after a capital or a digit (Mstar) is that name with the subscript star.
The first _ in a name starts the subscript: my_long_name_2 is shown as my with the subscript long_name_2, as Calcpad writes it. Names with digits and several underscores calculate normally; only the way they are typeset changes.

The same rule renames every use of a name, so you spell it one way throughout the sheet. Inside >> lines and calcpad fences the sheet’s spelling is used too: phi in a raw line is φ.

Units

Write a unit after a number. The engine checks and combines them:

a: 2 m; b: 350 mm
A: a * b -> m^2
v: 90 km/h -> m/s
t: 2 h + 30 min -> min
F: 10 N * 3 m -> J

a = 2 m
b = 350 mm
A = a·b = 2 m · 350 mm = 0.7 m²
v = 90 km/h = 25 m/s
t = 2 h + 30 min = 150 min
F = 10 N · 3 m = 30 J

² and ³ after a name or unit are ^2 and ^3. mm³ and mm^3 are the same.
A unit written after a number is never renamed, so 3 psi is a pressure and psi alone would be the Greek letter ψ.
Adding a length to a time is an error. Multiplying and dividing them is fine.
Several units in a sum convert to the first: 5 m + 30 cm is 5.3 m.

The whole subject, with the unit list and custom units, is in Units.

Converting the answer: `->`

-> unit converts the result. It must come last, before the note:

Mstar: 12 kN/m * (6 m)^2 / 8 -> kN*m | maximum bending moment
Mnmm: Mstar -> N*mm

M_star = 12 kN/m · (6 m)² / 8 = 54 kN·m    maximum bending moment
Mnmm = M_star = 54 kN·m = 54000000 N·mm

Without -> the engine chooses the unit itself, from the units in the formula. Use -> when you want a particular unit in the result, and always when the result goes into a report.

Notes

The first | outside brackets starts a note, a short comment shown beside the result in a muted style. || is the logical or, not a note. A note can contain LaTeX (| load at stage $i$).

Several per line

Separate quantities with ;. A note belongs to the last one:

a: 3; b: 4 | note for b
c: sqrt(a^2 + b^2)

a = 3
b = 4    note for b
c = √(a² + b²) = √(3² + 4²) = 5

Numbers and operators

You can write 1.23e6 or 2.5e-3. The engine has no exponent notation, so the compiler writes the plain number (1230000, 0.0025) and that is what the result shows.
Operators are + - * / ^ % and the comparisons < > <= >= == !=, with and and or. The Unicode forms ≤ ≥ ≠ ≡ ∧ ∨ × · ÷ − work too. In a condition a single = also means equal.
Calls take commas: max(a, b). The compiler writes the semicolon the engine wants.
Use abs(x) for an absolute value, not bars.
π (or pi) and e are built in. The other constants in the Insert tab (gravity, the speed of light, unit weights and so on) are snippets that insert a definition line such as g = 9.80665m/s^2; until you insert one, g is the unit gram. See the reference.

Vectors and matrices

v: [1, 2, 3]
A: [2, -1; -1, 2]

[1, 2, 3] is a vector; [1, 2; 3, 4] is a matrix with columns separated by commas and rows by semicolons. See Vectors and matrices.

Inputs: a quantity the reader can change

Put a ? in front of the value and the quantity becomes an input, with that value as its default:

L: ? 6 m | span
w: ? 12 kN/m | design load
M: w * L^2 / 8 -> kN*m | maximum moment

In Input mode L and w are boxes. Everywhere else the lines read as the quantities they are. A list of options ([Steel = 200 GPa, Timber = 11 GPa], or round brackets for radio buttons) and on or off (a checkbox) are inputs too. See Templates with inputs.

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