A new computational formula to nonlinear adjustment by parameters , in consideration of the second - order terms , is derived in this paper from the precise orthogonality condition equations to nonlinear least squares by analyzing the direct solving process and iterative computing method of the linearized model 在分析線性化的非線性參數(shù)平差的近似直接解法與迭代解法基礎(chǔ)上,利用非線性最小二乘的精確正交性條件方程,推導(dǎo)出顧及到二次項(xiàng)的非線性參數(shù)平差的一種新的計(jì)算公式。