SpheroidalQS[n,m,γ,z]
gives the angular spheroidal function
of the second kind.
SpheroidalQS
SpheroidalQS[n,m,γ,z]
gives the angular spheroidal function
of the second kind.
Details
- Mathematical function, suitable for both symbolic and numerical manipulation.
- The angular spheroidal functions satisfy the differential equation
with the spheroidal eigenvalue
given by SpheroidalEigenvalue[n,m,γ]. - SpheroidalQS[n,m,0,z] is equivalent to LegendreQ[n,m,z].
- SpheroidalQS[n,m,a,γ,z] gives spheroidal functions of type
. The types are specified as for LegendreP. - For certain special arguments, SpheroidalQS automatically evaluates to exact values.
- SpheroidalQS can be evaluated to arbitrary numerical precision.
- SpheroidalQS automatically threads over lists. »
Examples
open all close allBasic Examples (3)
Scope (23)
Numerical Evaluation (7)
SpheroidalQS[5, 1, .1, .3]SpheroidalQS[3, 2, 1., .2]N[SpheroidalQS[2, 1, 1 / 3, -11], 20]N[SpheroidalQS[1 / 4, 1 / 3, 1, 0, -11], 20]The precision of the output tracks the precision of the input:
SpheroidalQS[2, 2, 1 / 3, 0.211111111111111111]SpheroidalQS[2, 2, 1 / 3, 0.2111111111111111111111111]N[SpheroidalQS[23, 5, 2I, 2 / 3]]Evaluate efficiently at high precision:
SpheroidalQS[3, 2, 1, 2`100]//TimingSpheroidalQS[11, 0, 1 / 2, 5`200];//TimingCompute the elementwise values of an array using automatic threading:
SpheroidalQS[1 / 2, 1, 0, {{1 / 2, 0}, {0, 1 / 2}}]Or compute the matrix SpheroidalQS function using MatrixFunction:
MatrixFunction[SpheroidalQS[1 / 2, 1, 0, #]&, {{1 / 2, 0}, {0, 1 / 2}}]Compute average-case statistical intervals using Around:
SpheroidalQS[1, 0, 0, Around[1 / 2, 0.01]]Specific Values (4)
SpheroidalQS[n,m,0,x] is equivalent to the LegendreQ[n,m,x] function:
SpheroidalQS[n, m, 0, x]//FunctionExpand//QuietFind the first positive maximum of SpheroidalQS[4,0,1/2,x]:
xmax = x /. FindRoot[D[SpheroidalQS[4, 0, 1 / 2, x], x] == 0, {x, .5}]//QuietPlot[SpheroidalQS[4, 0, 1 / 2, x], {x, -1, 1.5}, Epilog -> Style[Point[{xmax, SpheroidalQS[4, 0, 1 / 2, xmax ]}], PointSize[Large], Red]]The SpheroidalQS function is equal to zero for half-integer parameters:
SpheroidalQS[1 / 2, 1 / 2, 2, x]//QuietDifferent SpheroidalQS types give different symbolic forms:
Table[SpheroidalQS[n, 0, 0, x], {n, 0, 2}]//FullSimplify//QuietVisualization (3)
Plot the SpheroidalQS function for various orders:
Plot[{SpheroidalQS[1, 0, 1, x], SpheroidalQS[2, 0, 1, x], SpheroidalQS[3, 0, 1, x], SpheroidalQS[4, 0, 1, x]}, {x, -1, 1}]ComplexContourPlot[Re[SpheroidalQS[3, 0, 1, z]], {z, -1 - I, 1 + I}, Contours -> 24]ComplexContourPlot[Im[SpheroidalQS[3, 0, 1, z]], {z, -1 - I, 1 + I}, Contours -> 24]Types 2 and 3 of SpheroidalQS functions have different branch cut structures:
Plot3D[Im[SpheroidalQS[2, 1, 2, x + I y]], {x, -1.5, 1.5}, {y, -0.5, 0.5}, Exclusions -> {{y == 0, Abs[x] > 1}}]Plot3D[Im[SpheroidalQS[2, 1, 3, x + I y]], {x, -1.5, 1.5}, {y, -0.5, 0.5}, Exclusions -> {{y == 0, -1 < x < 1}}]Function Properties (5)
Plot[{SpheroidalQS[1, 2, -x, 3], SpheroidalQS[1, 2, x, 3]}, {x, -1, 1}]
has both singularities and discontinuities for
:
FunctionSingularities[SpheroidalQS[2, 0, 1, x], x]//QuietFunctionDiscontinuities[SpheroidalQS[2, 0, 1, x], x]//Quiet
is neither non-decreasing nor non-increasing:
FunctionMonotonicity[SpheroidalQS[2, 0, 1, x], x]
is neither non-negative nor non-positive:
FunctionSign[SpheroidalQS[2, 0, 1, x], x]TraditionalForm formatting:
SpheroidalQS[n, m, c, η]//TraditionalFormDifferentiation (2)
The first derivative with respect to z:
D[SpheroidalQS[n, m, γ, z], z]Higher derivatives with respect to z:
Table[D[SpheroidalQS[n, m, γ, z], {z, k}], {k, 1, 3}]//FullSimplifyPlot the higher derivatives with respect to z when n=5, m=2 and γ=1:
Plot[Evaluate[% /. { n -> 5, m -> 2, γ -> 1}], {z, -1, 1}, PlotLegends -> {"First Derivative", "Second Derivative", "Third Derivative"}]Series Expansions (2)
Find the Taylor expansion using Series:
Series[SpheroidalQS[n, m, γ, x], {x, 0, 3}]//NormalPlots of the first three approximations around
:
terms = Normal@Table[Series[SpheroidalQS[2, 0, 5, x], {x, 0, m}], {m, 1, 5, 2}]//N;
Plot[{SpheroidalQS[2, 0, 5, x], terms}, {x, -1, 1}, MaxRecursion -> 1]The Taylor expansion at a generic point:
Series[SpheroidalQS[n, m, γ, x], {x, x0, 2}]// FullSimplifyGeneralizations & Extensions (2)
The different types (type 1 or type 2) of SpheroidalQS have different branch cut structures as for LegendreQ:
SpheroidalQS[n, m, 1, 0, x]SpheroidalQS[n, m, 2, 0, x]SpheroidalQS of different types numerically:
SpheroidalQS[1, 1 / 3, 11, 0.5]SpheroidalQS[1, 1 / 3, 1, 11, 0.5]SpheroidalQS[1, 1 / 3, 2, 11, 0.5]Applications (3)
Solve the spheroidal differential equation in terms of SpheroidalQS:
DSolve[(1 - x^2)y''[x] - 2x y'[x] + (SpheroidalEigenvalue[n, m, γ] + γ^2(1 - x^2) - (m^2/1 - x^2))y[x] == 0, y, x]Solve this spheroidal-type differential equation:
eqns = {(1 - a ^ 2 r ^ (2 z)) Derivative[2][w][z] + (-Log[r] - a ^ 2 r ^ (2 z) Log[r] - 2 Log[s] + 2 a ^ 2 r ^ (2 z) Log[s]) Derivative[1][w][z] + (a ^ 2 r ^ (2 z) Log[r] ^ 2 SpheroidalEigenvalue[ν, μ, γ] + (1 / (-1 + a ^ 2 r ^ (2 z))) ((-a ^ 2) r ^ (2 z) (-μ ^ 2 + (-1 + a ^ 2 r ^ (2 z)) ^ 2 γ ^ 2) Log[r] ^ 2 + (-1 + a ^ 4 r ^ (4 z)) Log[r] Log[s] - (-1 + a ^ 2 r ^ (2 z)) ^ 2 Log[s] ^ 2)) w[z] == 0};sol = Subscript[c, 1] s ^ z SpheroidalQS[ν, μ, γ, a r ^ z] + Subscript[c, 2] s ^ z SpheroidalPS[ν, μ, γ, a r ^ z]eqns /. w[z] -> sol//SimplifyPlot prolate and oblate versions of the same angular function:
{Plot[SpheroidalQS[2, 1, 5, x], {x, -1, 1}, MaxRecursion -> 1, PlotPoints -> 25], Plot[SpheroidalQS[2, 1, 5I, x], {x, -1, 1}, MaxRecursion -> 1, PlotPoints -> 25]}Properties & Relations (1)
SpheroidalQS is equivalent to type 2 LegendreQ when
:
SpheroidalQS[n, m, 0, x]When
, the spheroidal ODE simplifies to the Legendre ODE:
DSolve[((1 - x^2)y''[x] - 2x y'[x] + (SpheroidalEigenvalue[n, m, γ] + γ^2(1 - x^2) - (m^2/1 - x^2))y[x] == 0) /. γ -> 0, y, x]See Also
Tech Notes
Related Guides
Related Links
History
Introduced in 2007 (6.0)
Text
Wolfram Research (2007), SpheroidalQS, Wolfram Language function, https://reference.wolfram.com/language/ref/SpheroidalQS.html.
CMS
Wolfram Language. 2007. "SpheroidalQS." Wolfram Language & System Documentation Center. Wolfram Research. https://reference.wolfram.com/language/ref/SpheroidalQS.html.
APA
Wolfram Language. (2007). SpheroidalQS. Wolfram Language & System Documentation Center. Retrieved from https://reference.wolfram.com/language/ref/SpheroidalQS.html
BibTeX
@misc{reference.wolfram_2026_spheroidalqs, author="Wolfram Research", title="{SpheroidalQS}", year="2007", howpublished="\url{https://reference.wolfram.com/language/ref/SpheroidalQS.html}", note=[Accessed: 13-June-2026]}
BibLaTeX
@online{reference.wolfram_2026_spheroidalqs, organization={Wolfram Research}, title={SpheroidalQS}, year={2007}, url={https://reference.wolfram.com/language/ref/SpheroidalQS.html}, note=[Accessed: 13-June-2026]}