DNEQNF 算法求解非线性方程组

楚香饭

错误提示很重要，为什么每次都不给出？

楚香饭

用 Module 封装，你得调用 F90 接口，F77接口不行

[Fortran] 纯文本查看 复制代码

Module function_equation
contains
  Subroutine fcn(xx, yy, nn)
    Implicit None
    Integer nn
    Double Precision xx(nn), yy(nn)
    yy(1) = xx(1)**2 + xx(2)**2 - 5D0
    yy(2) = (xx(1)+1D0)*xx(2) - (3D0*xx(1)+1D0)
  End Subroutine fcn
End Module function_equation

Program main_test
  Use neqnf_int
  Use umach_int
  Use function_equation
  Implicit None
  Double Precision, Parameter :: errrel = 1D-7
  Integer, Parameter :: n = 2
  Integer, Parameter :: itmax = 200
  Double Precision x_guess(2), ans(2), fnorm
  x_guess = (1D0, 1D0)
  Call neqnf(fcn, ans, xguess=x_guess, fnorm=fnorm)
  Print *, ans
End Program main_test