wrightOmega - Wright omega function

Syntax

Description

wrightOmega(x) computes the Wright omega function of x.

wrightOmega(A) computes the Wright omega function of each element of A.

Input Arguments

x	Number, symbolic variable, or symbolic expression.
A	Vector or matrix of numbers, symbolic variables, or symbolic expressions.

Definitions

Wright omega Function

The Wright omega function is defined in terms of the Lambert W function:

The Wright omega function ω(x) is a solution of the equation Y + log(Y) = X.

Examples

Compute the Wright omega function for these numbers. Because these numbers are not symbolic objects, you get floating-point results:

wrightOmega(1/2)

ans =
    0.7662

wrightOmega(pi)

ans =
    2.3061

wrightOmega(-1+i*pi)

ans =
    -1

Compute the Wright omega function for the numbers converted to symbolic objects. For most symbolic (exact) numbers, wrightOmega returns unresolved symbolic calls:

wrightOmega(sym(1/2))

ans =
wrightOmega(1/2)

wrightOmega(sym(pi))

ans =
wrightOmega(pi)

For some exact numbers, wrightOmega has special values:

wrightOmega(-1+i*sym(pi))

ans =
    -1

Compute the Wright omega function for x and sin(x) + x*exp(x). For symbolic variables and expressions, wrightOmega returns unresolved symbolic calls:

syms x
wrightOmega(x)
wrightOmega(sin(x) + x*exp(x))

ans =
wrightOmega(x)
 
ans =
wrightOmega(sin(x) + x*exp(x))

Now compute the derivatives of these expressions:

diff(wrightOmega(x), x, 2)
diff(wrightOmega(sin(x) + x*exp(x)), x)

ans =
wrightOmega(x)/(wrightOmega(x) + 1)^2 -...
wrightOmega(x)^2/(wrightOmega(x) + 1)^3
 
ans =
(wrightOmega(sin(x) + x*exp(x))*(cos(x) +...
exp(x) + x*exp(x)))/(wrightOmega(sin(x) + x*exp(x)) + 1)

Compute the Wright omega function for elements of matrix M and vector V:

M =[0 pi; 1/3 -pi];
V = sym([0; -1+i*pi]);
wrightOmega(M)
wrightOmega(V)

ans =
    0.5671    2.3061
    0.6959    0.0415
 
ans =
 lambertw(0, 1)
             -1

References

Corless, R. M. and D. J. Jeffrey. "The Wright omega Function." Artificial Intelligence, Automated Reasoning, and Symbolic Computation (J. Calmet, B. Benhamou, O. Caprotti, L. Henocque, and V. Sorge, eds.). Berlin: Springer-Verlag, 2002, pp. 76-89.

See Also

lambertW | log

How To

• Special Functions of Applied Mathematics

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