https://epubs.siam.org/doi/abs/10.1137/080734510?casa_token=xljjjEZTnc8AAAAA:zi9tkpMc5wsqCcaW7WWnhXXv56MxTd4IBob3oXT1UV6_G09PxSNDOR0BFj3nBJJ_vsTs30qs53M