fprintf在经历循环时不会打印
我正在尝试在文档中打印某些内容，但它只适用于我尝试过的第一个h值！ 我试图弄清楚自己，但我不得不在不到一个小时的时间内将这些代码交给我的教授，所以我有点绝望。 ：/
#include #include double euler(double v0, double *t0, double h, double (*f)(double)); double dv(double v); int main(){ double vlim, t = 0; double *pt = &t; double h0 = 1.e-7; vlim = euler(0, pt, h0, dv); printf("O tempo ea velocidade limite para um passo de %.0e s sao respectivamente:\n", h0); printf("%.0e se %lf mm/s.\n\n", *pt, vlim); double h = h0, v = 0; do { *pt = 0; v = euler(0, pt, h, dv); h /= 5.; } while (fabs(v-vlim)/v > 1e-5); printf("O passo necessario para atingir a convergencia na velocidade limite e' %.1e s.\n",h); return 0; } double euler(double y, double *x, double h, double (*f)(double)){ FILE *arq = fopen("bolha.dat","w+"); double y0, eps = 1e-4; do{ y0 = y; y = y0 + h*f(y0); // Metodo de Euler *x += h; fprintf(arq, "%.1e\t%.7lf\n", *x, y); } while (fabs((y-y0)/y) > eps); fclose(arq); return y; } dv不相关，所以我没有发布。 看起来它在循环中是非常愚蠢的，因为如果我把h0 = 2.e-8（这是我正在尝试打印的值）它适用于该值。
我能够通过使文件成为euler函数的参数然后在循环之后再次在另一个文件上调用它来修复它。 这解决了问题，但我仍然不明白为什么以前没有工作。
#include #include double euler(double v0, double *t0, double h, double (*f)(double), FILE *arquivo); double dv(double v); int main(){ FILE *saida = fopen("bolhateste.dat","w+"); double vlim, t = 0; double *pt = &t; double h0 = 1.e-7; vlim = euler(0, pt, h0, dv, saida); printf("O tempo ea velocidade limite para um passo de %.0e s sao respectivamente:\n", h0); printf("%.0e se %lf mm/s.\n\n", *pt, vlim); double h = h0, v = 0; do { *pt = 0; v = euler(0, pt, h, dv, saida); h /= 5.; } while (fabs(v-vlim)/v > 1e-5); saida = fopen("bolha.dat","w+"); euler(0, pt, h, dv, saida); printf("O passo necessario para atingir a convergencia na velocidade limite e' %.1e s.\n",h); return 0; } double euler(double y, double *x, double h, double (*f)(double), FILE *arquivo){ double y0, eps = 1e-4; do{ y0 = y; y = y0 + h*f(y0); // Metodo de Euler *x += h; fprintf(arquivo, "%.1e\t%.7lf\n", *x, y); } while (fabs((y-y0)/y) > eps); return y; }