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NonThreadable

is an attribute that can be assigned to a symbol f to indicate that f and f[arg1,arg2,…] should not combine with other list arguments in arithmetic and many other functions that work with lists.

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NonThreadable

NonThreadable

is an attribute that can be assigned to a symbol f to indicate that f and f[arg1,arg2,…] should not combine with other list arguments in arithmetic and many other functions that work with lists.

Details

  • The NonThreadable attribute is typically used for symbols that represent non-scalar quantities.
  • VectorSymbol, MatrixSymbol and ArraySymbol have the NonThreadable attribute.
  • Most standard built‐in functions that produce array results have the NonThreadable attribute.
  • Expressions whose heads are non-threadable objects are non-threadable.
  • Expressions obtained by applying Listable functions to non-threadable objects are non-threadable.

Examples

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Basic Examples  (1)

Give the NonThreadable attribute to symbol x:

Wolfram Language code: SetAttributes[x, NonThreadable]

Arithmetic operations do not combine x with list elements:

Wolfram Language code: x + y + {{1, 2}, {3, 4}}

Expressions with non-threadable heads are non-threadable:

Wolfram Language code: x[1]y[2]{1, 2, 3}

Expressions obtained by applying Listable functions to non-threadable objects are non-threadable:

Wolfram Language code: Cos[x[1, 2]] + Cos[y[1, 2]] + {1, 2, 3}

Scope  (4)

ArraySymbol has the NonThreadable attribute:

Wolfram Language code: Attributes[ArraySymbol]

Arithmetic operations do not combine symbolic arrays with list elements:

Wolfram Language code: ArraySymbol["a", {p, q, r}] + {1, 2, 3}

SymbolicOnesArray has the NonThreadable attribute:

Wolfram Language code: Attributes[SymbolicOnesArray]

A symbolic matrix of ones is not added to matrix elements:

Wolfram Language code: SymbolicOnesArray[{2, 2}] + {{1, 2}, {3, 4}}

When the symbolic matrix is converted to an explicit matrix, the matrices are added correctly:

Wolfram Language code: Normal[%]

Inverse has the NonThreadable attribute:

Wolfram Language code: Attributes[Inverse]

Arithmetic operations do not combine expressions with head Inverse with list elements:

Wolfram Language code: Inverse[a] + {{1, 2}, {3, 4}}

Dot does not have the NonThreadable attribute:

Wolfram Language code: Attributes[Dot]

Expressions with head Dot are threadable, unless they are known to be nonscalars:

Wolfram Language code: x.y + {1, 2}
Wolfram Language code: VectorSymbol["u", n].VectorSymbol["v", n] + {1, 2}
Wolfram Language code: MatrixSymbol["a", {n, n}].VectorSymbol["v", n] + {1, 2}
Wolfram Research (2024), NonThreadable, Wolfram Language function, https://reference.wolfram.com/language/ref/NonThreadable.html.

Text

Wolfram Research (2024), NonThreadable, Wolfram Language function, https://reference.wolfram.com/language/ref/NonThreadable.html.

CMS

Wolfram Language. 2024. "NonThreadable." Wolfram Language & System Documentation Center. Wolfram Research. https://reference.wolfram.com/language/ref/NonThreadable.html.

APA

Wolfram Language. (2024). NonThreadable. Wolfram Language & System Documentation Center. Retrieved from https://reference.wolfram.com/language/ref/NonThreadable.html

BibTeX

@misc{reference.wolfram_2026_nonthreadable, author="Wolfram Research", title="{NonThreadable}", year="2024", howpublished="\url{https://reference.wolfram.com/language/ref/NonThreadable.html}", note=[Accessed: 13-June-2026]}

BibLaTeX

@online{reference.wolfram_2026_nonthreadable, organization={Wolfram Research}, title={NonThreadable}, year={2024}, url={https://reference.wolfram.com/language/ref/NonThreadable.html}, note=[Accessed: 13-June-2026]}