使用函数作为另一个函数输入

Question

您好我编码很新但我有一个非常复杂的pshysics问题需要用cpp来解决我遇到了一些问题

#include <stdio.h>
#include <cmath>
#include <iostream>

using namespace std;

double delta_x(double x, double n)
{
    return x/n;
}

double theta(delta_x(double x,double n),double i, double a)
{
    return atan(abs(2*a*((delta_x(x,n)*i)-50)-(0.01)));
}

Codeblox告诉我以下错误：

|9|error: expected primary-expression before 'double'|
|9|error: expected primary-expression before 'double'|
|9|error: expected primary-expression before 'double'|
|9|error: expected primary-expression before 'double'|
|9|error: expression list treated as compound expression in initializer [-fpermissive]|
|10|error: expected ',' or ';' before '{' token|
|20|error: 'theta' cannot be used as a function|

提前致谢

Answer 1

无需将delta_x传递回theta：

double delta_x(double x, double n)
{
    return x/n;
}

double theta(double i, double a)
{
    return atan(abs(2*a*((delta_x(i,a)*i)-50)-(0.01)));
}