Function validate_matrixAndQuregAreCompatible

quest/src/core/validation.cpp:2576–2601

void validate_matrixDimMatchesTargets(DiagMatr  matr, int numTargs, const char* caller) { assertMatrixDimMatchesTargs(matr, numTargs, caller); }

void validate_matrixAndQuregAreCompatible(FullStateDiagMatr matr, Qureg qureg, bool expecOnly, const char* caller) {

    // we do not need to define this function for the other matrix types,
    // since their validation will happen through validation of the
    // user-given list of target qubits. But we do need to define it for
    // FullStatedDiagMatr to check both distribution compatibility, and
    // that dimensions match. When expecOnly=true, we relax the necessity
    // that the distributions match; one or both can be distributed

    tokenSubs vars = {
        {"${NUM_MATR_QUBITS}",  matr.numQubits},
        {"${NUM_QUREG_QUBITS}", qureg.numQubits}};

    // dimensions must match
    assertThat(matr.numQubits == qureg.numQubits, report::FULL_STATE_DIAG_MATR_MISMATCHES_QUREG_DIM, vars, caller);

    // when matrix is duplicated on every node, its application is trivial
    if (!matr.isDistributed)
        return;

    // but when it's distributed, so too must be the qureg; the precise reason why is 
    // specific to whether qureg is a statevector or density matrix, but boils down
    // to there being no communication buffers available to broadcast matr
    if (!expecOnly)
        assertThat(qureg.isDistributed, report::FULL_STATE_DIAG_MATR_IS_DISTRIB_BUT_QUREG_ISNT, caller); // did not pass vars
}