例句與造句

1. of unknown regression coefficient ft under the linear restriction r = r and its convergence, that is : 2 . the optimalities of covariance-improved estimator sequence under three mde crlterions; 3
   求出了在線性約束r=r下未知回歸系數(shù)_1的協(xié)方差改進(jìn)估計序列，及此序列的收斂性：2
2. based on [ 4 ], the author adds a linear restriction r = r to this sur system, and discusses the estimator and the optimalities of unknown regression coefficient ft in the sur system under the linear restriction
   本文將在文獻(xiàn)[4]的基礎(chǔ)上，對此sur系統(tǒng)增加一線性約束r=r，討論在此線性約束r=r下半相依回歸系統(tǒng)中未知回歸系數(shù)_1的估計及其優(yōu)良性問題。
3. in the late 30 or 40 years, many scholars have a lot of studies on a seemingly unrelated regression ( sdr ) system with two linear regression models, and some important results are obtained : zellner ( 1962 ) put forward two-stage estimator ( tse ); based on zellner " s, lin chun-shi ( 1984 ) obtained the sufficient and necessary condition of two-stage estimator; chen chang-hua ( 1986 ) discussed the tse and its optimalities without any condition for designed-matrix x; ulteriorly, wang song-gui and van li-qing ( 1997 ) obtained an iteration sequence of estimator by using the covariance-improved approach; liu jin-shan ( 1994 ), li wen and lin ju-gan ( 1997 ) generalized the covariance-improved estimator respectively
   半相依回歸系統(tǒng)是由兩個誤差項相關(guān)的線性回歸方程組成的系統(tǒng)。近三、四十年來，已有很多的學(xué)者對這類半相依回歸系統(tǒng)進(jìn)行了大量的研究，作出了十分重要的成果：zellner(1962)提出了所謂兩步估計法；在其基礎(chǔ)上，林春士(1984)得出了兩步估計的充要條件，陳昌華(1986)討論了對設(shè)計矩陣不作任何要求的兩步估計及其優(yōu)良性；進(jìn)一步地，王松貴、嚴(yán)利清(1997)利用協(xié)方差改進(jìn)法獲得了參數(shù)的一個迭代估計序列，劉金山(1994)，李文、林舉干(1997)則分別對協(xié)方差改進(jìn)估計進(jìn)行了推廣。
4. It's difficult to find optimalities in a sentence. 用optimalities造句挺難的