/* Dasproc C - 2019
William Handi Wijaya
0087

Memprediksi nilai kedalaman
*/

#include <stdio.h> //scanf and printf definition
#include <math.h> // pow definition
#define R_COEFF 0.014 //const of N
#define SLOPE 0.0015 // slope of concrete
#define FLOW 1000 //flow desired
#define WIDTH 15 // width of concrete
double cal_flow(double);
int within_desired(double);
int main()
{
    double depth, // input - depth of concrete
           temp_flow, //flow based on user's input of depth
           difference, // output - difference of flow desired and user's flow
           error; // output - error of guess
    int flag = -1, // loop's sentinel
        i = 0; //initiate begins of program
    //intro program
    printf("\nAt a depth of 5.0000 feet, the flow is 641.3255 cubic feet per second.");
    //program loop
    while(flag != 1)
    {
        if(i == 0) //begin of program
        {
            printf("\nEnter your initial guess for the channel depth when the flow is %d cubic feet per second", FLOW);
            printf("\nEnter guess>");
        }
        else //if guess's flow still not in range
            printf("\nEnter guess>");
        //get the depth
        scanf("%lf", &depth);
        //calculate the flow
        temp_flow = cal_flow(depth);

        difference = FLOW - temp_flow;
        error = (difference / FLOW) * 100;
        //printing the result
        printf("\nDepth: %.3f Flow: %.3f cfs Target: 1000 cfs Difference: %.3f Error: %.3f percent", depth, temp_flow, difference, error);

        flag = within_desired(temp_flow);
        i = -1;
    }
}
//function to calculate the flow
double cal_flow(double depth)
{
    double area, hydraulic_radius, temp_flow;

    hydraulic_radius = (depth * WIDTH) / ((2 * depth) + WIDTH);
    area = depth * WIDTH;
    temp_flow = (1.486/R_COEFF) * (area * pow(cbrt(hydraulic_radius), 2)) * sqrt(SLOPE);

    return temp_flow;
}
//function to verify the guess
int within_desired(double num)
{
    if(num >= ((FLOW - ((0.1/100) * FLOW))) && (num <= (FLOW + ((0.1/100) * FLOW))))
        return 1;
    return 0;
}