LOG in SoftMaker PlanMaker 2026: bases, examples and domain errors

For LOG(x,b), the answer is the exponent y satisfying b^y=x. For instance, 2^3=8, hence LOG(8,2)=3. A logarithm converts multiplication into addition, and exponential growth into a rate or period calculation. Use it to find powers of ten, binary powers, growth milestones, ratios and logarithmic-scale transforms. LOG, LOG10 and LN are not three spellings of the same function: LOG accepts an optional base (default 10), LOG10 explicitly means base 10, and LN means base e. SoftMaker 2026 LOG; LN; EXP.

=LOG(Number [, Base])

The square brackets in SoftMaker’s notation show that Base is optional; do not type square brackets into a working formula.

Important evidence distinction: the 2026 and 2024 SoftMaker LOG pages explicitly require Number > 0 and default Base to 10. They do not explicitly list a Base-domain rule or per-input error codes. The mathematical real-logarithm domain additionally requires Base > 0 and Base != 1; an exact PlanMaker runtime error for invalid bases has not been observed. 2026 LOG; 2024 LOG.

The function is documented as LOG, without a second English alias in the referenced pages. Formula entry begins with =. The English examples use comma argument separation and decimal points. SoftMaker documents that number separators can come from the computer’s region or PlanMaker’s custom settings; the localized function spelling and list separator are not guaranteed by this English page. In an international installation check the Formula → Function dialog, the decimal settings, and the resulting formula spelling. 2026 formula-entry help; Edit tab.

Create A1=Number, B1=Base, C1=Formula, and D1=Expected output. Type the numeric A/B inputs and put the indicated exact formula into column C. These independently calculated expected outputs can be compared to the worksheet display after the reader performs a native run; they are not PlanMaker screenshots or execution observations.

For example, enter A3=8, B3=2 and C3==LOG(A3,B3). If C2 contains =LOG(A2), it exercises the documented default base 10 regardless of the B2 value: explicitly set =LOG(A2,B2) to make the base come from a cell. A2:A9 and B2:B9 are numeric inputs, not stored formula strings. Format C with 8–10 decimal places when investigating rounding.

Single-cell calculations

• =LOG(100) → independently 2, matching SoftMaker’s example.
• =LOG(8,2) → independently 3, matching SoftMaker’s example.
• =LOG(10^0.1234) → independently approximately 0.1234, matching SoftMaker’s example.
• =LOG(4096,2) → independently 12.
• =LOG(1,7) → independently 0.
• =LOG(0.01) → independently -2; a logarithm can be negative although its input is positive.

Let A12 be an initial value of 5000, B12 a target of 10000, and C12 a per-period growth factor of 1.08 (that is, 8% growth per period). Solve 5000 × 1.08^n = 10000 for n:

=LOG(B12/A12,C12)

Independently expected 9.006468… periods. If the quantity only updates after whole periods, the minimum full period count under this idealized constant-growth model is 10 (round upward, not to the nearest integer). You may separately use a rounding function for this planning choice, but this example intentionally displays the fractional mathematical threshold. Units: C12 is a multiplier (1.08), not the percentage number 8. If C12=8%, use 1+C12 as the logarithm base. For decreasing balances, a base between 0 and 1 can also be mathematically meaningful, but real-world model assumptions must be checked.

The vendor evidence for LOG’s base and syntax is SoftMaker’s LOG entry; the growth equation and result are an independent algebraic derivation, not a SoftMaker worked example.

If a data size doubles each step, =LOG(1024,2) gives independently expected 10 doubling steps because 2^10=1024. With A15=1024 and B15=2, compute =LOG(A15,B15). In an independent check =LN(A15)/LN(B15) is mathematically equal by the change-of-base identity. This is useful when a second formula is desired to help catch an accidental default of base 10. The vendor documents LN separately, while the equality is a mathematical identity; neither formula was executed in PlanMaker in this research run.

Given a signal-ratio value A18=1000, =LOG(A18) independently gives 3, meaning a thousandfold ratio has three orders of magnitude in base 10. For an input A19=0.00001, =-LOG(A19) independently gives 5, an example of the negative base-10 logarithm convention used by some scientific scales. This is a numerical transform, not proof that all domain-specific scientific units, offsets or calibrations are covered by the formula.

If values are measured with units, form a dimensionless ratio (for example, measured value divided by a reference value in the same units) before applying LOG. Do not take a logarithm of a negative measured difference, which is outside the real-number domain.

SoftMaker PlanMaker 2026 error values and formula entry, checked 2026-10-13, support generic error and entry guidance, not specific PlanMaker LOG outputs for each invalid formula.

• SoftMaker PlanMaker 2026 LOG — authoritative syntax/default/domain.
• SoftMaker PlanMaker 2024 LOG — separate version verification.
• PlanMaker 2026 LOG10 — explicit base-10 variant.
• PlanMaker 2026 LN — natural logarithms.
• PlanMaker 2026 EXP — exponentiation with base e.
• PlanMaker 2026 POWER — powers.
• PlanMaker 2026 formula entry, error values and regional numeric settings.
• Microsoft Excel LOG — separately verified Excel syntax, not a PlanMaker execution.

Official-reference check date: 2026-10-13. PlanMaker 2026 and 2024 reference entries and independent Microsoft documentation were read separately. Numeric examples use Python’s math.log/math.log10 and inverse exponentiation as independent checks. No native PlanMaker execution, no Excel execution, no .xlsx round-trip, no screenshots were performed.