c - gsl akima 样条的插值误差

Question

我使用以下代码收到“gsl: interp.c:150: ERROR: interpolation error”。一些谷歌搜索说，当您尝试使用 interp 函数进行推断时，会发生此错误，但我不明白这是如何发生的。帮助将不胜感激。谢谢。

函数randomground()仅返回一个随机数( double )。

#define NSTEPS 100   

int main()
{
           int j, q, space = 1, refine = 100;
           double xi = 0.0, tx[2*NSTEPS] = {0}, theight[2*NSTEPS] = {0};

           double terrain[(int) (2*NSTEPS*100)] = {0};
           double terrainsl[(int) (2*NSTEPS*100)] = {0};

            for (j = 0; j < 2*NSTEPS; j++)
            {
                tx[j] = (double) j*space;
                theight[j] = randomground();
            }

            gsl_interp_accel *acc = gsl_interp_accel_alloc();
            gsl_spline *spline = gsl_spline_alloc(gsl_interp_akima, 2*NSTEPS);
            gsl_spline_init(spline, tx, theight, 2*NSTEPS);

            for (q = 0; q< 2*NSTEPS*100; q++)
            {
                terrain[q] = gsl_spline_eval(spline,xi,acc);
                terrainsl[q] = gsl_spline_eval_deriv(spline,xi,acc);
                xi = xi+(double) space/refine;
            }
return 0;
}

Answer 1

通过向 tx 和 theight 添加额外的元素解决了该问题。我猜这就是你要求我做的，@ViniciusMiranda。代码现在显示为

                double tx[2*NSTEPS+1] = {0}, theight[2*NSTEPS+1] = {0};
                double terrain[(int) (2*NSTEPS*100)] = {0};
                double terrainsl[(int) (2*NSTEPS*100)] = {0};

            for (j = 0; j < 2*NSTEPS+1; j++)
            {
                tx[j] = (double) j*space;
                theight[j] = randomground();
            }

            gsl_interp_accel *acc = gsl_interp_accel_alloc();
            gsl_spline *spline = gsl_spline_alloc(gsl_interp_akima, 2*NSTEPS+1);
            gsl_spline_init(spline, tx, theight, 2*NSTEPS+1);

            for (q = 0; q< 2*NSTEPS*100; q++)
            {
                terrain[q] = gsl_spline_eval(spline,xi,acc);
                terrainsl[q] = gsl_spline_eval_deriv(spline,xi,acc);
                xi = xi+(double) space/refine;
            }

我仍然不明白为什么需要此修复。