qlat.field_double — Real-Double Field Operations

Source: qlat/qlat/field_double.py

Note: Update this document when updating the source file.

Outline

• set_checkers(field) — set checkerboard pattern on a real-double field.

• set_double_from_complex(field, cf) — real part of complex field.

• set_complex_from_double(field, sf) — promote real field to complex.

• set_abs_from_complex(field, cf) — element-wise absolute value.

• set_ratio_double(field, sf1, sf2) — element-wise ratio sf1 / sf2.

• less_than_double(field, sf2, mask) — element-wise comparison.

• invert_double(field) — element-wise inversion 1 / field.

• multiply_double(field, factor) — element-wise field × field product.

Overview

This module provides element-wise manipulation routines for fields whose element type is ElemTypeRealD (real double precision). Each function delegates to the corresponding C++ implementation in qlat.c after verifying element-type compatibility via assert statements.

These utilities are typically used for scalar observable fields such as plaquette densities, topological charge densities, or mask/weight fields.

API Reference

set_checkers(field)

Fill field with a checkerboard pattern (±1 on alternating sites). Marks as possibly unnecessary in the source.

Raises: AssertionError if field.ctype is not ElemTypeRealD.

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set_double_from_complex(field, cf)

Store the real part of complex field cf into real-double field field.

Parameter	Type	Description
field	FieldBase	Destination, must be ElemTypeRealD.
cf	FieldBase	Source, must be ElemTypeComplexD.

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set_complex_from_double(field, sf)

Promote real-double field sf into complex field field (imaginary part set to zero).

Parameter	Type	Description
field	FieldBase	Destination, must be ElemTypeComplexD.
sf	FieldBase	Source, must be ElemTypeRealD.

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set_abs_from_complex(field, cf)

Store the element-wise absolute value of complex field cf into real-double field field.

Parameter	Type	Description
field	FieldBase	Destination, must be ElemTypeRealD.
cf	FieldBase	Source, must be ElemTypeComplexD.

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set_ratio_double(field, sf1, sf2)

Compute the element-wise ratio sf1 / sf2 and store the result in field. All three fields must be ElemTypeRealD.

Parameter	Type	Description
field	FieldBase	Destination.
sf1	FieldBase	Numerator.
sf2	FieldBase	Denominator.

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less_than_double(field, sf2, mask)

For each element, set the corresponding entry in mask to 1.0 if field[i] < sf2[i], otherwise 0.0. All fields must be ElemTypeRealD.

Parameter	Type	Description
field	FieldBase	Left-hand side of comparison.
sf2	FieldBase	Right-hand side of comparison.
mask	FieldBase	Output mask field.

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invert_double(field)

Replace every element of field with its reciprocal 1 / element.

Raises: AssertionError if field.ctype is not ElemTypeRealD.

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multiply_double(field, factor)

Element-wise product field[i] *= factor[i]. Both fields must be ElemTypeRealD.

Parameter	Type	Description
field	FieldBase	Field to be modified in-place.
factor	FieldBase	Multiplicative factor field.

Examples

import qlat as q
import qlat_utils as qu

q.begin_with_mpi([[1, 1, 1, 4]])

geo = q.Geometry(q.Coordinate([4, 4, 4, 8]))
f_real = q.Field(q.ElemTypeRealD, geo, 1)
f_complex = q.Field(q.ElemTypeComplexD, geo, 1)
f_real.set_rand(q.RngState("seed"), 1.0, -1.0)
f_complex.set_zero()

# Convert complex field to real (takes real part)
q.field_double.set_double_from_complex(f_real, f_complex)

# Promote real field to complex
f_complex2 = q.Field(q.ElemTypeComplexD, geo, 1)
f_real2 = q.Field(q.ElemTypeRealD, geo, 1)
f_real2.set_rand(q.RngState("seed2"), 1.0, -1.0)
q.field_double.set_complex_from_double(f_complex2, f_real2)

q.end_with_mpi()