Functions for modifying existing Pauli data structures. More...

Functions
void	sortPauliStrSumLexicographic (PauliStrSum sum)

void	sortPauliStrSumMagnitude (PauliStrSum sum)

Detailed Description

Functions for modifying existing Pauli data structures.

Function Documentation

◆ sortPauliStrSumLexicographic()

void sortPauliStrSumLexicographic ( PauliStrSum sum )

Reorders the terms within a sum of weighted Pauli strings so that the Pauli strings are ordered lexicographically.

Formulae

Let \( H = \) sum, satisfying

\[ H = \sum\limits_j c_j \, \hat{\sigma}_j \]

where \( c_j \) is the coefficient of the \( j \)-th PauliStr \( \hat{\sigma}_j \).

This function applies the permutation \( \pi \) to \( H \), whereby

\[ H = \sum\limits_j c_{\pi(j)} \, \hat{\sigma}_{\pi(j)} \]

such that

\[ \hat{\sigma}_{\pi(i)} <_{lex} \hat{\sigma}_{\pi(j)} \ \forall \ \pi(i) < \pi(j). \]

Parameters

[in,out] sum a weighted sum of Pauli strings to reorder.

Exceptions

error

if sum is not initialised.

See also

sortPauliStrSumMagnitude()

Author: Vasco Ferreira

Definition at line 310 of file paulis.cpp.

                                                              {
    validate_pauliStrSumFields(sum, __func__);
 
    auto lexSort = [&](qindex i, qindex j) {
        PauliStr strI = sum.strings[i];
        PauliStr strJ = sum.strings[j];
        return std::tie(strI.highPaulis, strI.lowPaulis) < std::tie(strJ.highPaulis, strJ.lowPaulis);
    };
 
    auto errFunc = [&](size_t numBytes) { validate_tempAllocSucceeded(false, numBytes, __func__); };
    paulis_sortTermsViaComparator(sum, lexSort, errFunc);
}

◆ sortPauliStrSumMagnitude()

void sortPauliStrSumMagnitude ( PauliStrSum sum )

Reorders the terms within a sum of weighted Pauli strings such that coefficients are ordered with decreasing magnitude.

Formulae