EXPONDIST in ONLYOFFICE Spreadsheet Editor

• Introduced: Original introduction release is not established by the checked sources.
• Available: Listed in current unversioned ONLYOFFICE help, checked October 18, 2026.
• Implementation inspected: Official SDKJS v10.0.0.169, commit 3679e0375a758d7dc59d31337a45461be3525ed8. The snapshot does not prove identical behavior in every installed editor.
• Retired or deprecated: These sources do not establish retirement or formal deprecation. A legacy name alone does not mean the function has been removed.
• Testing: Numerical examples are independent mathematical expectations, and implementation discrepancies are labeled source predictions. No ONLYOFFICE application or calculation-engine execution was performed.

The examples use English function names and commas. Use your locale’s argument separator if different. Retain full precision in formulas; round only the displayed result. The examples describe function mechanics under the stated model, rather than establishing that your observations follow that model.

=EXPONDIST(x, lambda, cumulative)

The implementation registers exactly three arguments. Help describes nonnegative x, positive lambda and a logical cumulative flag. TRUE requests the exponential CDF and FALSE is documented as requesting the PDF. Lambda is a rate: with hours as the x unit, it is measured per hour, and mean waiting time is 1/lambda.

Important source discrepancy: SDKJS v10.0.0.169 converts the third argument to Boolean, then rejects arg2<=0. It checks the cumulative flag where a rate check would be expected. Consequently FALSE is rejected before its density branch can run. The same guard does not check whether lambda is positive. These are inspected-code predictions, not observed application results. Use the modern EXPON.DIST spelling for new density formulas, and check an installed editor before a large migration.

1. In A2 enter 0.5, representing half an hour.
2. In B2 enter 2, representing a rate of two events per hour.
3. In C2 enter =EXPONDIST(A2,B2,TRUE).
4. Independently calculate =1-EXP(-B2*A2) as the mathematical comparison.
5. Both formulas are mathematically expected to give 0.632120558829 for this positive-rate cumulative case.

Now change A2 to 1. The expectation becomes 1-exp(-2), or 0.864664716763. At A2 = 0, the expectation is 0. These CDF values describe the chance that waiting time is at most the chosen threshold, not a count of events and not the density at that threshold.

The last two rows diagnose missing validation; they are not useful exponential models. Validate the rate independently rather than accepting a numeric result as evidence that inputs were meaningful. The error name above refers to the implementation’s not_numeric error category; no application display was captured.

An existing positive-rate workbook may calculate the probability of waiting between 0.5 and 1 hour as =EXPONDIST(1,2,TRUE)-EXPONDIST(0.5,2,TRUE). The independent expectation is 0.232544157935, from exp(-1)-exp(-2). Preserve the same rate and units in both calls.

To migrate, reproduce this interval with two EXPON.DIST calls using TRUE, and compare ordinary numeric cases before replacing formulas across the workbook. Check FALSE calls separately: their behavior is precisely where the inspected implementations differ. Also check any array inputs, since the legacy body reduces arrays to a first element while the modern function uses an array helper. Changing the spelling is not a blanket compatibility repair.

For a survival probability, =EXP(-2*1) directly gives approximately 0.135335283237. This avoids cancellation from 1-CDF for very small tails. For minutes rather than hours, use a rate of 2/60 and a threshold of 60, rather than treating 2 as a per-minute rate.

Negative x is rejected by the inspected guard. FALSE is also rejected regardless of a valid positive rate. Nonnumeric conversion errors propagate; quoted text flags and cell/array coercion should not be assumed portable. Extremely large products can underflow the exponential and mask a small nonzero tail.

Even a correct CDF is conditional on an exponential model with constant rate. A continuous PDF would be a density per unit of x, not the probability of one exact waiting time; it may exceed 1. Formal deprecation is not established here: the reason for caution is the specific inspected behavior, rather than the age of the name.

Recalculate representative formulas when moving a workbook between editors. Matching names do not guarantee identical argument coercion, array behavior, numerical precision or error handling. The scalar formulas here do not establish automatic spill behavior or a general import/export guarantee.

• EXP
• LN

• ONLYOFFICE EXPONDIST help, checked October 18, 2026.
• Official SDKJS implementation, 6376–6438, tag v10.0.0.169 and exact commit above.