atlas Library · Script File
extended_misc.at
Definitions in source order
x_rep type
set_type x_rep = (ratvec v, mat theta)
Fields: v, theta
ExtParam type
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
canonical_g (RealForm G) = ratveccanonical_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))
canonical_g (KGBElt x) = ratveccanonical_g (KType t) = ratveccanonical_g (Param p) = ratvecsome variants of Cayley transformsL25
use vector-based cross/Cayley when possibleL27
cross
cross (int s,Param p) = Paramalso defined in basic.at, coherent_irreducible.at, synthetic.at, coherent_characters.at
Cayley
Cayley (int s,Param p) = Paramalso defined in basic.at
Cayley_set 3 overloads
Cayley_set (int j,Param p) = [Param]Cayley transform as a set (actually an array, but order doesn't matter)
Cayley_set (int j, int k, Param p) = [Param]doubly iterated Cayley
Cayley_set ([int] kappa, Param p) = [Param]uniform syntax for single or iterated Cayley
twist 2 overloads
twist (mat delta,KGBElt x) = KGBEltaction of delta on KGB for general distinguished delta if delta=distinguished_involution(real_form(x)) then twist(delta,x)=twist(x)
twist (mat delta,Param p)also defined in basic.at, nilpotent_orbits.at
is_fixed 4 overloads
is_fixed (mat delta, Param p) = boolis_fixed (ratvec gamma, mat delta, KGBElt x,KGBElt y) = boolis_fixed (mat delta, KGBElt x) = boolwhether KGBElt (pair) is fixed by twist by matrix delta
is_fixed (mat delta, KGBElt x, KGBElt y) = boolalso defined in synthetic.at
Stuff related to KGBL79
|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.atL80
in_A
in_A (x_rep(v,theta)) = boolin_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
is_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
square_is_central (InnerClass ic,x_rep(v,theta)) = booluse the function defined in parameters.at
also defined in synthetic.at, parameters.at
root_datum
root_datum (ExtParam E) = RootDatumalso 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
rho (ExtParam E) = ratvecalso defined in basic.at, nilpotent_orbit_partitions.at, nilpotent_orbits.at
rho_check
rho_check (ExtParam E) = ratvecalso defined in basic.at
dual_parameter
dual_parameter (ExtParam (ic, delta, gamma, lambda, theta, g, l, omega, tau,t)) = ExtParamlog_z
log_z (mat delta, vec lambda_rho, vec l, vec tau,vec t) = ratin 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
log_zeta (mat delta, vec lambda, vec l,vec tau,vec t) = ratmodulo 1
also in this file at line 123
log_z
log_z (ExtParam E) = ratalso in this file at line 116
log_zeta
log_zeta (ExtParam E) = ratalso in this file at line 118
compute x,y, the one-sided parameters of an extended parameterL126
x
x (ExtParam E) = KGBEltalso defined in basic.at
y
y (ExtParam E) = KGBEltassumes integral |E.gamma|
parameter
parameter (ExtParam E) = Paramrecover 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
integrality_datum (ExtParam E) = RootDatumalso defined in basic.at, nilpotent_orbits.at
translate_to_dominant
translate_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
valid ( ExtParam(ic,delta,gamma,lambda_rho,theta,g,l,omega,tau,t)) = boolfor debugging: test that an extended parameter satisfies the defining conditions
fixed
fixed (mat delta, [Param] B) = [Param]select delta-fixed elements from B
filter delta-fixed elements
fixed_block_of
fixed_block_of (mat delta, Param p) = [Param]select delta-fixed elements from block_of(p)
fixed_block
fixed_block (mat delta, Param p) = ([Param],int)format
format (ExtParam E) = stringalso defined in cyclotomic.at, polynomial.at, cyclotomicMat.at, bracket.at
short_format
short_format (ExtParam E) = stringalso defined in G2_unitary_dual.at
long_format
long_format (ExtParam E) = stringdisplay
display (ExtParam E) = voidalso defined in extParamPol.at
display_one_line
display_one_line (ExtParam E) = voidGenerated from atlas-scripts at commit 648506c (2026-10-13).