# SiegelTheta

SiegelTheta[Ω,s]

gives the Siegel theta function with Riemann modular matrix Ω and vector s.

SiegelTheta[{ν1,ν2},Ω,s]

gives the Siegel theta function with characteristics ν1 and ν2.

# Details • Mathematical function, suitable for both symbolic and numerical manipulation.
• The matrix Ω must be symmetric, with positive definite imaginary part.
• If Ω is a p×p matrix, the vectors s and v or νi must have length p.
• , where n ranges over all possible vectors in the p-dimensional integer lattice.
• , where n ranges over all possible vectors in the p-dimensional integer lattice.
• SiegelTheta can be evaluated to arbitrary numerical precision.

# Examples

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## Basic Examples(3)

Evaluate numerically:

Plot over a subset of the reals:

Plot over a subset of the complexes:

## Scope(7)

### Numerical Evaluation(3)

Evaluate numerically:

Evaluate to high precision:

The precision of the output tracks the precision of the input:

Evaluate efficiently at high precision:

### Specific Values(2)

Value at zero:

Find a value of x for which Re[SiegelTheta[{{I,1},{1, I}},{x,x/3}]]=1:

### Visualization(2)

Plot the SiegelTheta function for various parameters:

Plot the real part of :

Plot the imaginary part of :

## Generalizations & Extensions(2)

SiegelTheta with characteristics and :

SiegelTheta with characteristics simplifies symbolically for special arguments:

## Applications(2)

Plot of the absolute value of SiegelTheta in the complex plane:

Define an Abelian function:

Plot of the real part:

## Properties & Relations(2)

In one dimension, SiegelTheta coincides with the EllipticTheta functions:

SiegelTheta satisfies the equations:

## Possible Issues(2)

SiegelTheta requires a symmetric matrix: The symmetric part:

Machine precision may be insufficient to obtain a correct answer:

Use arbitrary precision to check the result:

## Neat Examples(1)

Introduced in 2007
(6.0)