Function getRandomOrIdentityApiMatrix

tests/unit/operations.cpp:415–462

template <NumQubitsFlag Targs, ArgsFlag Args>
auto getRandomOrIdentityApiMatrix(int numTargs, int elemsFlag) {

    DEMAND(
        Args == diagmatr ||
        Args == diagpower ||
        Args == compmatr );
    DEMAND( 
        elemsFlag == 0 ||
        elemsFlag == 1 ||
        elemsFlag == 2 );

    qmatrix qm;
    if (elemsFlag == 0)
        qm = getZeroMatrix(getPow2(numTargs));
    if (elemsFlag == 1)
        qm = getIdentityMatrix(getPow2(numTargs));
    if (elemsFlag == 2)
        qm = (Args == compmatr)?
            getRandomUnitary(numTargs) : 
            getRandomDiagonalUnitary(numTargs);
        
    if constexpr (Args == compmatr && Targs == one) 
        return getCompMatr1(qm);

    if constexpr (Args == compmatr && Targs == two)
        return getCompMatr2(qm);

    if constexpr (Args == compmatr && Targs == any) {
        CompMatr cm = createCompMatr(numTargs); // must be freed
        setCompMatr(cm, qm);
        return cm;
    }

    qvector dv = getDiagonals(qm);
    constexpr bool diag = (Args == diagmatr || Args == diagpower);

    if constexpr (diag && Targs == one)
        return getDiagMatr1(dv);

    if constexpr (diag && Targs == two)
        return getDiagMatr2(dv);

    if constexpr (diag && Targs == any) {
        DiagMatr dm = createDiagMatr(numTargs); // must be freed
        setDiagMatr(dm, dv);
        return dm;
    }
}

template <NumQubitsFlag Targs, ArgsFlag Args> auto getZeroApiMatrix    (int numTargs) { return getRandomOrIdentityApiMatrix<Targs,Args>(numTargs, 0); }
template <NumQubitsFlag Targs, ArgsFlag Args> auto getIdentityApiMatrix(int numTargs) { return getRandomOrIdentityApiMatrix<Targs,Args>(numTargs, 1); }