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atlas Library · Script File

extended_misc.at

Source
atlas-scripts/extended_misc.at (209 lines)
Definitions
42
Loads
Loaded by
extParamPol.at KL_polynomial_matrices.at extended.at extended_types.at bigMatrices.at

Definitions in source order

x_rep type

L6
set_type x_rep = (ratvec v, mat theta)

Fields: v, theta

ExtParam type

L7
set_type ExtParam =
  ( InnerClass ic, mat delta
  , ratvec gamma, vec lambda_rho, mat theta
  , ratvec g, vec l, mat omega
  , vec tau, vec t
  )

Fields: ic, delta, gamma, lambda_rho, theta, g, l, omega, tau, t

canonical_g 4 overloads

L20canonical_g (RealForm G) = ratvec
canonical_g(x) returns a dominant regular element g such that e(g)=x^2
This only depends on the real_form(x), in fact only on its square class
the implementation depends on base_grading_vector(G) being dominant.
An alternative that does not depend on that (recently ensured) circumstance:
canonical_g(RealForm G)= ratvec: shift_g_regular(G,square(G))
L21canonical_g (KGBElt x) = ratvec
L22canonical_g (KType t) = ratvec
L23canonical_g (Param p) = ratvec
some variants of Cayley transforms
L25
use vector-based cross/Cayley when possible
L27

cross

L31cross (int s,Param p) = Param

also defined in basic.at, coherent_irreducible.at, synthetic.at, coherent_characters.at

Cayley

L36Cayley (int s,Param p) = Param

also defined in basic.at

Cayley_set 3 overloads

L42Cayley_set (int j,Param p) = [Param]
Cayley transform as a set (actually an array, but order doesn't matter)
L47Cayley_set (int j, int k, Param p) = [Param]
doubly iterated Cayley
L51Cayley_set ([int] kappa, Param p) = [Param]
uniform syntax for single or iterated Cayley

twist 2 overloads

L60twist (mat delta,KGBElt x) = KGBElt
action of delta on KGB for general distinguished delta
if delta=distinguished_involution(real_form(x)) then twist(delta,x)=twist(x)
L63twist (mat delta,Param p)

also defined in basic.at, nilpotent_orbits.at

is_fixed 4 overloads

L67is_fixed (mat delta, Param p) = bool
L70is_fixed (ratvec gamma, mat delta, KGBElt x,KGBElt y) = bool
L74is_fixed (mat delta, KGBElt x) = bool
whether KGBElt (pair) is fixed by twist by matrix delta
L75is_fixed (mat delta, KGBElt x, KGBElt y) = bool

also defined in synthetic.at

Stuff related to KGB
L79
|x_rep = (ratvec v, mat theta)| is used to represent a KGB element $x$ by
$\xi=exp_1(v)\sigma_w\xi_0$ where $\exp_1: v\mapsto\exp(2i\pi v)$ maps
$X_*\otimes\Q$ to the torus, and $\theta = w\circ\delta_0$ is involution.
Relation to atlas built-in: |torus_factor(x)=2*v-rho_check(G)|
Jeff prefers to work with the (shifted, halved) "actual torus factor" |v|
also called "unnormalized torus factor" in parameters.at
L80

in_A

L91in_A (x_rep(v,theta)) = bool
in_A@x_rep: test if e(v) is in A:=(H^{-theta})^0 (validity test)
concretely: whether rational vector (1+theta)v lies in lattice (1+theta)X_*

is_equivalent

L98is_equivalent (x_rep r1, x_rep r2) = bool
$H$-conjugation of elements determined by |x_rep| values
implicit: $\exp_1(v_i)\theta_i=\exp_1(v_i)\sigma_i*\xi_0$ (for $i=1,2$)
in same extended group for $G$
test: $\theta_1=\theta_2$, and $\exp_1(v_1-v_2)\in A=(H^{\theta_1})^0$

square_is_central

L101square_is_central (InnerClass ic,x_rep(v,theta)) = bool
use the function defined in parameters.at

also defined in synthetic.at, parameters.at

root_datum

L105root_datum (ExtParam E) = RootDatum

also defined in basic.at, W_reps.at, K_Nilpotent.at, sommers.at, parabolics.at, K.at, nilpotent_orbits.at, W_classes.at, character_tables.at, springer_tables.at, disconnected.at, cyclotomic_Lie_algebra.at, bracket.at, exceptional.at

rho

L106rho (ExtParam E) = ratvec

also defined in basic.at, nilpotent_orbit_partitions.at, nilpotent_orbits.at

rho_check

L107rho_check (ExtParam E) = ratvec

also defined in basic.at

dual_parameter

L109dual_parameter (ExtParam (ic, delta, gamma, lambda, theta, g, l, omega, tau,t)) = ExtParam

log_z

L116log_z (mat delta, vec lambda_rho, vec l, vec tau,vec t) = rat
in PFTR: z=i^<tau,(delta_0-1)l>(-1)^<lambda,t>
PFTR:delta_0 is ^delta here
modulo 1

also in this file at line 121

log_zeta

L118log_zeta (mat delta, vec lambda, vec l,vec tau,vec t) = rat
modulo 1

also in this file at line 123

log_z

L121log_z (ExtParam E) = rat

also in this file at line 116

log_zeta

L123log_zeta (ExtParam E) = rat

also in this file at line 118

compute x,y, the one-sided parameters of an extended parameter
L126

x

L128x (ExtParam E) = KGBElt

also defined in basic.at

y

L131y (ExtParam E) = KGBElt
assumes integral |E.gamma|

parameter

L139parameter (ExtParam E) = Param
recover ordinary Param value from ExtParam; could be defined as
set parameter (ExtParam E) = Param: parameter(x(E),y(E),E.gamma)

actually this is better: use |(E.x,E.lambda,E.gamma)|

also defined in basic.at, L_packet.at, K.at, parameters.at

integrality_datum

L141integrality_datum (ExtParam E) = RootDatum

also defined in basic.at, nilpotent_orbits.at

translate_to_dominant

L152translate_to_dominant (ExtParam (ic,delta,gamma,lambda_rho,theta,g,l,omega,tau,t):E) = (ExtParam,vec)
assume gamma(E) is integrally dominant
translate by sum of roots to make it dominant
return (new extended parameter, sum of roots)
see nonintegral.at
*** should not need this any more, now that gamma is allowed to be
    integrally dominant
However, since not all functions allow that, it is still needed

also defined in Weylgroup.at

valid

L161valid ( ExtParam(ic,delta,gamma,lambda_rho,theta,g,l,omega,tau,t)) = bool
for debugging:
test that an extended parameter satisfies the defining conditions

fixed

L183fixed (mat delta, [Param] B) = [Param]
select delta-fixed elements from B
filter delta-fixed elements

fixed_block_of

L187fixed_block_of (mat delta, Param p) = [Param]
select delta-fixed elements from block_of(p)

fixed_block

L189fixed_block (mat delta, Param p) = ([Param],int)

format

L192format (ExtParam E) = string

also defined in cyclotomic.at, polynomial.at, cyclotomicMat.at, bracket.at

short_format

L203short_format (ExtParam E) = string

also defined in G2_unitary_dual.at

long_format

L205long_format (ExtParam E) = string

display

L208display (ExtParam E) = void

also defined in extParamPol.at

display_one_line

L209display_one_line (ExtParam E) = void

Generated from atlas-scripts at commit 648506c (2026-10-13).