Surd [x,n]
gives the real-valued n^(th) root of x.
Surd
Surd [x,n]
gives the real-valued n^(th) root of x.
Details
- Surd [x,n] returns the real-valued n^(th) root of real-valued x for odd n.
- Surd [x,n] returns the principal n^(th) root for non-negative real-valued x and even n.
- For symbolic x in Surd [x,n], x is assumed to be real valued.
- Surd can be evaluated to arbitrary numerical precision.
- Surd automatically threads over lists. »
- In StandardForm , Surd [x,n] formats as .
- can be entered as surd, and moves between the fields.
- Surd can be used with Interval and CenteredInterval objects. »
Examples
open all close allBasic Examples (5)
Scope (31)
Numerical Evaluation (5)
Evaluate numerically:
Evaluate to high precision:
The precision of the output tracks the precision of the input:
Evaluate efficiently at high precision:
Compute the elementwise values of an array using automatic threading:
Or compute the matrix Surd function using MatrixFunction :
Compute worst-case guaranteed intervals using Interval and CenteredInterval objects:
Or compute average-case statistical intervals using Around :
Specific Values (4)
Values at fixed points:
Evaluate symbolically:
Values at infinity:
Find a value of x for which (RadicalBox[x, 2, MultilineFunction -> None, SurdForm -> True])=1.5:
Substitute in the result:
Visualize the result:
Visualization (4)
Plot the Surd function for various orders:
Visualize the absolute value and argument (sign) of for odd n:
The function has the same absolute value but a different argument for :
Compare the real and imaginary parts of and for even n:
Polar plot with :
Function Properties (8)
Surd [x,n] is defined for all real x when n is a positive, odd integer:
For positive, even n, it is defined for non-negative x:
For negative n, 0 is removed from the domain:
Surd is not defined for nonreal complex values:
Surd [x,n] achieves all non-negative real values when n is a positive even integer:
For positive odd n, its range is the whole real line:
For negative n, 0 is removed from the range:
Surd [x,n] is not an analytic function of x for any integer n:
is increasing for positive :
Decreasing for negative even :
Indefinite for negative odd :
is injective for :
Visualize for :
And it is surjective onto for odd, positive , but not other values of :
Visualize for :
has indefinite sign for odd :
It is non-negative on its real domain for even :
in general has both singularities and discontinuities at zero:
However, for positive odd it is continuous at the origin:
is neither convex nor concave for odd :
On its domain of definition, it is concave for positive even and convex of negative even :
Differentiation (3)
The first derivative with respect to x:
Higher derivatives with respect to x:
Plot the higher derivatives with respect to x:
Formula for the ^(th) derivative with respect to x:
Integration (3)
Compute the indefinite integral using Integrate :
Verify the anti-derivative:
Definite integral:
More integrals:
Series Expansions (4)
Find the Taylor expansion using Series :
Plots of the first three approximations around :
General term in the series expansion using SeriesCoefficient :
The first-order Fourier series:
The Taylor expansion at a generic point:
Applications (1)
With , the real vector field corresponding to the complex function is , and the trajectories that follow the field satisfy the differential equation . The implicit solution is for real , which corresponds to a family of circles that are tangent to the real axis at the origin:
In polar coordinates, the trajectories are for any real :
More generally, for where is an integer, the streamlines follow for constant :
This also works for negative powers:
For odd powers, care must be taken to ensure the first argument to Surd is non-negative:
Properties & Relations (3)
Possible Issues (1)
Neat Examples (1)
Plot a composition of Surd :
Related Guides
Related Links
History
Text
Wolfram Research (2012), Surd, Wolfram Language function, https://reference.wolfram.com/language/ref/Surd.html.
CMS
Wolfram Language. 2012. "Surd." Wolfram Language & System Documentation Center. Wolfram Research. https://reference.wolfram.com/language/ref/Surd.html.
APA
Wolfram Language. (2012). Surd. Wolfram Language & System Documentation Center. Retrieved from https://reference.wolfram.com/language/ref/Surd.html
BibTeX
@misc{reference.wolfram_2025_surd, author="Wolfram Research", title="{Surd}", year="2012", howpublished="\url{https://reference.wolfram.com/language/ref/Surd.html}", note=[Accessed: 10-January-2026]}
BibLaTeX
@online{reference.wolfram_2025_surd, organization={Wolfram Research}, title={Surd}, year={2012}, url={https://reference.wolfram.com/language/ref/Surd.html}, note=[Accessed: 10-January-2026]}