ERR:DOMAIN
Texas Instruments TI-84 Calculator
Severity: MinorWhat it means
ERR:DOMAIN means you gave a function an input value outside its valid range.
For example, taking the square root of a negative number or the logarithm of zero.
Check the mathematical requirements of the function you are using.
Affected Models
- TI-84 Plus
- TI-84 Plus CE
- TI-84 Plus Silver Edition
- TI-83 Plus
- TI-Nspire (TI-84 mode)
Common Causes
- Square root of a negative number (in Real mode)
- Logarithm of zero or a negative number
- Inverse trig function with argument outside -1 to 1 (sin⁻¹, cos⁻¹)
- nCr or nPr with invalid arguments (negative or non-integer)
- Statistical function with invalid data
How to Fix It
-
Check the input value for the function.
Each math function has a valid domain:
sqrt: x >= 0.
log/ln: x > 0.
sin⁻¹/cos⁻¹: -1 <= x <= 1. -
If you need the square root of a negative number, switch to a+bi mode.
Press MODE, scroll to a+bi, press ENTER.
Now sqrt(-1) returns i instead of ERR:DOMAIN. -
For statistics: check that your lists contain valid data.
Statistical tests and regressions require specific data formats.
Empty lists, mismatched list lengths, or non-numeric entries cause ERR:DOMAIN.
Frequently Asked Questions
What does domain mean in math?
The domain of a function is the set of all valid input values.
For example, sqrt(x) has a domain of x >= 0 because you cannot take the square root of a negative number (in real numbers).
What is a+bi mode?
a+bi mode enables complex number calculations.
In this mode, the calculator can work with imaginary numbers (i = sqrt(-1)).
This avoids ERR:DOMAIN for operations like sqrt(-4), which returns 2i.