ERR:DOMAIN
Texas Instruments TI-84 Calculator
Severity: MinorWhat Does This Error Mean?
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
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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.
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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.
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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.