Function createCompMatr

quest/src/api/matrices.cpp:213–245

extern "C" CompMatr createCompMatr(int numQubits) {
    validate_envIsInit(__func__);
    validate_newCompMatrParams(numQubits, __func__);

    // validation ensures these never overflow
    qindex numRows = powerOf2(numQubits);
    qindex numElems = numRows * numRows;

    // attempt to allocate 1D memory
    qcomp* cpuMem = cpu_allocArray(numElems); // nullptr if failed
    qcomp* gpuMem = nullptr;
    if (getQuESTEnv().isGpuAccelerated)
        gpuMem = gpu_allocArray(numElems); // nullptr if failed

    // prepare output CompMatr (avoiding C++20 designated initialiser)
    CompMatr out;
    out.numQubits = numQubits;
    out.numRows = numRows;

    // attemptedly allocate (un-initialised) flags in the heap so that struct copies are mutable
    out.isApproxUnitary    = util_allocEpsilonSensitiveHeapFlag(); // nullptr if failed
    out.isApproxHermitian  = util_allocEpsilonSensitiveHeapFlag();
    out.wasGpuSynced = cpu_allocHeapFlag(); // nullptr if failed

    // attemptedly allocate 2D alias for 1D CPU memory
    out.cpuElems = cpu_allocAndInitMatrixWrapper(cpuMem, numRows); // nullptr if failed
    out.cpuElemsFlat = cpuMem;
    out.gpuElemsFlat = gpuMem;

    validateMatrixAllocs(out, __func__);
    setInitialHeapFlags(out);
    return out;
}


extern "C" DiagMatr createDiagMatr(int numQubits) {