easteregg.c

/*  This program does some handy handling of significant
figures that is handy for physics  152

Author:  Bryce Lobdell
Email:  blobdell@purdue.edu
Date:  2/11/99

*/



#include "stdio.h"
#include "math.h"

#define J 74
#define P 80
#define E 69
#define M 77
#define C 67
#define D 68
#define A 65
#define S 83
#define I 73
#define R 82
#define Q 81
#define HELP 63


char gospel[2000]=
{"	Jesus replied, \"I am the bread of life.  No one\n\
who comes to me will ever be hungry again.  Those who\n\
believe in me will never thirst.  But you haven't\n\
believed in me even though you have seen me.  However,\n\
those the Father has given me will come to me, and I\n\
will never reject them.  For I have come down from\n\
heaven to do the will of God who sent me, not to do\n\
what I want.  And this is the will of God, that I\n\
should not lose even one of all those he has given me,\n\
but that I should raise them to eternal life at the\n\
last day.  For it is my Father's will that all who see\n\
his Son and believe in him should have eternal - that I\n\
should raise them at the last day.\"  (John 6:35-40)\n"};

#define uchar unsigned char
#define uint unsigned int
#define ulong unsinged long

struct number
	{
	float val;
	float delta;
	};



char *strupr(char *string)
{
int counter;
char *index;

counter = 0;

do {
	index = string + counter;
	if ((*index >= 97) && (*index <= 122))
		*index -= 32;
	counter++;
	} while (*index != 0);

return string;
}




void shownum(struct number num)
{
printf("Val = %.12e \xF1 %.8e\n\n",num.val,num.delta);

}


struct number getnum(void)
{
struct number num;

printf("Number: ");
scanf("%f",&(num.val));
printf("Uncertainty: ");
scanf("%f",&(num.delta));


return num;
}


void help(void)
{

printf("Command Help:\nE  Enter Data to Variable\nM  Multiply\nD  Divide\n");
printf("A  Add\nS  Subtract\nP  Print Variable Data\nI  Inverse\n");
printf("R  Root\nC  Clear Screen\nQ  Quit\n\n");

}


struct number mult(struct number num1,struct number num2)
{
struct number num;

num.val = num1.val * num2.val;
num.delta = num.val * ((num1.delta/num1.val) + (num2.delta/num2.val));

return num;
}





struct number div(struct number num1,struct number num2)
{
struct number num;

num.val = num1.val / num2.val;
num.delta = num.val * ((num1.delta/num1.val) + (num2.delta/num2.val));

return num;
}


struct number add(struct number num1,struct number num2)
{
struct number num;

num.val = num1.val + num2.val;
num.delta = num1.delta + num2.delta;

return num;
}


struct number sub(struct number num1,struct number num2)
{
struct number num;

num.val = num1.val - num2.val;
num.delta = num1.delta + num2.delta;

return num;
}



struct number inv(struct number num)
{

num.delta = (1 / num.val) * (num.delta / num.val);
num.val = 1 / num.val;

return num;
}


struct number root(struct number num)
{

num.delta = num.delta / (2 * sqrt(num.val));
num.val = sqrt(num.val);

return num;
}



int selectvar(void)
{
int varnum;
char varstr[20];
printf("Select a Variable (A to Z): ");
scanf("%s",varstr);
strupr(varstr);
varnum = (int)varstr[0];
varnum -= 65;

if ((varnum < 0) || (varnum > 25))
	varnum = -1;

return varnum;
}



main(void)
{
char command[20];
int quit,var1,var2,ans;
struct number variables[26];

quit = 1;

printf("PHYS 152 Uncertainty Math\n");
printf("Enter ? for help\n\n");

do {
	scanf("%s",command);
	strupr(command);

	switch((int)(command[0]))
		{
		case (P):
			{
			var1 = selectvar();
			if (var1 == -1)
				{
				printf("Not a valid Variable\n");
				break;
				}
			shownum(variables[var1]);
			break;
			}
		case (E):
			{
			var1 = selectvar();
			if (var1 == -1)
				{
				printf("Invalid Variable\n");
				break;
				}
			variables[var1] = getnum();
			break;
			}
		case (M):
			{
			printf("Select 1st operand, 2nd operand and Answer Variables\n");
			var1 = selectvar();
			var2 = selectvar();
			ans = selectvar();
			if ((var1 == -1) || (var2 == -1) || (ans == -1))
				{
				printf("Invalid Variable\n");
				break;
				}
			variables[ans] = mult(variables[var1],variables[var2]);
			shownum(variables[ans]);
			break;
			}
		case (D):
			{
			printf("Select 1st operand, 2nd operand and Answer Variables\n");
			var1 = selectvar();
			var2 = selectvar();
			ans = selectvar();
			if ((var1 == -1) || (var2 == -1) || (ans == -1))
				{
				printf("Invalid Variable\n");
				break;
				}
			variables[ans] = div(variables[var1],variables[var2]);
			shownum(variables[ans]);
			break;
			}
		case (A):
			{
			printf("Select 1st operand, 2nd operand and Answer Variables\n");
			var1 = selectvar();
			var2 = selectvar();
			ans = selectvar();
			if ((var1 == -1) || (var2 == -1) || (ans == -1))
				{
				printf("Invalid Variable\n");
				break;
				}
			variables[ans] = add(variables[var1],variables[var2]);
			shownum(variables[ans]);
			break;
			}
		case (S):
			{
			printf("Select 1st operand, 2nd operand and Answer Variables\n");
			var1 = selectvar();
			var2 = selectvar();
			ans = selectvar();
			if ((var1 == -1) || (var2 == -1) || (ans == -1))
				{
				printf("Invalid Variable\n");
				break;
				}
			variables[ans] = sub(variables[var1],variables[var2]);
			shownum(variables[ans]);
			break;
			}
		case (I):
			{
			printf("Select operand and Answer Variables\n");
			var1 = selectvar();
			ans = selectvar();
			if ((var1 == -1) || (ans == -1))
				{
				printf("Invalid Variable\n");
				break;
				}
			variables[ans] = inv(variables[var1]);
			shownum(variables[ans]);
			break;
			}
		case (C):
			{
			printf("\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n");
			break;
         }
		case (R):
			{
			printf("Select operand and Answer Variables\n");
			var1 = selectvar();
			ans = selectvar();
			if ((var1 == -1) || (ans == -1))
				{
				printf("Invalid Variable\n");
				break;
				}
			variables[ans] = root(variables[var1]);
			shownum(variables[ans]);
			break;
			}
		case (Q):
			{
			quit = 0;
			break;
			}
		case (J):
			{
			printf("%s\n",gospel);
			break;
			}
		case (HELP):
			{
			help();
			break;
			}
		default:
			printf("Invalid Command\n");
		}

	} while (quit);


return 0;
}