some math function in c which i wrote 10 years ago

math.c

#include <stdio.h>
#include <conio.h>
#include <stdlib.h>
#include <math.h>

#define TRUE 1
#define FALSE 0
#define MAX_NUMBER 1000
#define POW_OF_e 1.00
void prime(void){

	unsigned int i,a;
	unsigned char chk_first;
	_clrscr();
	for(i=2;i<MAX_NUMBER;i++){
		chk_first= TRUE;
		for(a=2;a<=i/2;a++){
			if((i%a)==0){
				chk_first=FALSE;
			}
		}
		if(chk_first){
			printf("%u is a Prime Number.\r\n",i);
		}
	}
}
void perfect(void){
	unsigned int i,a,s;
	_clrscr();
	for( i = 1; i < MAX_NUMBER ; i++){
		s = 0;
		for(a = 2 ; a <= i / 2 ; a++){ //=========================> my pitfall
			s += ( (i % a) == 0 ) ? a : 0;
		}
		if(i == ++s){
			printf("%u is a Perfect Number.\r\n",i);
		}
	}
}
void sum(void){
	unsigned int i,s=0;
	_clrscr();
	for( i = 1; i <= MAX_NUMBER ; i++){
		s += i;
	}
	printf("S=1+2+3+...+%u=%u\r\n",MAX_NUMBER,s);
}
void minmaxave(void){
	unsigned int i,n,max=0,min=0,l,s=0;
	_clrscr();
	printf("Enter Number of Inputs:\0");
	scanf("%u",&n);
	for(i=1;i<=n;i++){
		printf("Enter %u's Number:\0",i);
		scanf("%u",&l);
		s+=l;
		if(i==1){
			min=max=l;
		}
		else{
			if(l<min){
				min=l;
			}
			if(l>max){
				max=l;
			}
		}
	}
	printf("\nMinimum = %u.\r\n Maximum = %u. \r\n\0",min,max);
	printf("Average = %f\r\n\0",((double)s)/n);
}
void sinsumpro(void){
	unsigned int i,n;
	double x,s=0.00,p=1.00;
	_clrscr();
	printf("Enter N:\0");
	scanf("%u",&n);
	printf("N=%u\r\n\0",n);
	printf("Enter X:\0");
	scanf("%lf",&x); //======================>my pitfall
	printf("X=%f\r\n\0",x);
	for(i=1;i<=n;i++){
		s+=sin(i*x);
		p*=sin(i*x);
	}
	printf("\r\nS=Sin(x)+Sin(2*x)+...+Sin(%u*x) = %f\r\n\0",n,s);
	printf("P=Sin(x)*Sin(2*x)*...*Sin(%u*x) = %f\r\n\0",n,p);
}
void doreverse(void){
	unsigned int n;
	unsigned long reverse(unsigned int);
	_clrscr();
	printf("Enter N (0...65535):\0");
	scanf("%u",&n);
	printf("Reverse of %u is %u\r\n\0",n,reverse(n));
}
unsigned long reverse(unsigned int n){
	unsigned long num_no = (unsigned int)(log10(n)+1);
	unsigned long result=0;
	int i;
	for(i=num_no-1;i>=0;i--){
		result+=(unsigned long)(pow(10,num_no-1-i)*(n/ (unsigned int) pow(10,i)));
		n-=(n/ (unsigned int)pow(10,i))*(unsigned int)(unsigned int)pow(10,i);
	}
	return result;
}
void doc(void){
	long c(unsigned int, unsigned int);
	unsigned long fact(int);
	unsigned int a,b;
	long cr;
	_clrscr();
	printf("Getting A and B of C(A,B)\r\n------------------------------\r\n\0");
	printf("Enter A:\0");
	scanf("%u",&a);
	printf("Enter B:\0");
	scanf("%u",&b);
	if((cr =c(a,b))==-1){
		printf("\r\nError !!!\a\r\n A Must be smaller than B or equal to B.\r\n\0");
	}else{
		printf("C(%d,%d) = %u\r\n\0",a,b,cr);
	}
}
unsigned long fact(int d){
	unsigned int i;
	unsigned long r=1;
	if(d <2){
		return 1;
	}else{
		for(i=1;i<=d;i++){
			r*=i;
		}
		return r;
	}
}

long c(unsigned int n, unsigned int m){
	if(n>m){
		return(-1);
	}else{
		return(fact(m))/(fact(n)*fact(m-n));
	}
}
void sumonlympown(void){
	unsigned int m,n,i,j;
	unsigned int s1=0,s2=0;
	_clrscr();
	printf("Enter M:\0");
	scanf("%u",&m);
	printf("Enter N:\0");
	scanf("%u",&n);
	
	//for(j=1;j<=m;j++){
	//	s1+=m;
	//}
	s1 = m;
	//for(i=1;i<=n-2;i++){

	for(i=1;i<n;i++){
		for(j=1;j<=m;j++){
			s2+=s1;
		}
		s1=s2;
		s2=0;
	}
	printf("M^N = %u \r\n\0",s1);
}
void printascii(void){
	unsigned char x=1,y=1;
	unsigned int i;
	_clrscr();
	for(i=0;i<=255;i++){
		_gotoxy(x,y);
		printf("%u",i);
		_putch((unsigned char)i);
		y++;
		if(y>26){
			y=1;
			x+=7;
		}
	}
}
void gcdlcm(void){
	unsigned int a,b,aa,bb,t;
	_clrscr();
	printf("Enter A:\0");
	scanf("%u",&a);
	printf("Enter B:\0");
	scanf("%u",&b);
	if(a<b){
		aa=b;
		bb=a;
	}else{
		aa=a;
		bb=b;
	}
	while((aa%bb)!=0){
		t=bb; //was wrong in book
		bb=aa%bb;
		aa=t;
	}
	printf("Greatest Common Divisor is: %u\r\n\0",bb);
	printf("Least Common Multiple is: %u",(a*b)/bb);
}
void fibonachi(void){
	unsigned long a1=1,a2=1,b;
	unsigned int m,c;
	_clrscr();
	do{
	printf("Enter M(to show M sequence of Fibonachi Series)(Max. 65535):\0");
	scanf("%u",&m);
	}while(m<2);
	printf("%u-%u\0",a1,a2);
	for(c=3;c<=m;c++){
		b=a1;
		a1=a2;
		a2=b+a2;
		printf("-%u\0",a2);
	}
}
void isperfect(void){
	unsigned int n,i,s=0;
	_clrscr();
	do{
		printf("Enter N (not smaller than 2): \0");
		scanf("%u",&n);
	}while(n<2);
	for(i=1;i<=n/2;i++){
		s+=(n%i==0)?i:0;
	}
	if(n==s){
		printf("%u is a perfect number.\r\n\0",n);
	}else{
		printf("%u is not a perfect number.\r\n\0",n);
	}
}
void pascaltriangle(void){
	unsigned int a,n;
	void draw_apb_n(unsigned int);
	_clrscr();
	printf("Enter N (smaller than 13): \0");
	scanf("%u",&n);
	_clrscr();
	for(a=0;a<=n;a++){
		draw_apb_n(a);
		printf("\r\n\0");
	}

}
void draw_apb_n(unsigned int n){
	unsigned int k;
	for(k=0;k<=n;k++){
		_gotoxy(k*4+1,_wherey());
		printf("%lu",(unsigned long)c(k,n));
	}
}
void drawafunciton(void){
	double a=-40.00;
	unsigned char b;
	_clrscr();
	_textcolor(9);
	_gotoxy(1,12);
	for(b=1;b<=80;b++){//pitfall: may infinite loop: should not use double float point in loop
		_cprintf("-\0");
	}
	for(b=1;b<=25;b++){
		_gotoxy(40,b);
		_cprintf("|\0");
	}
	_gotoxy(1,1);
	_textcolor(12);
	do{
		_gotoxy(40+(int)a,(int)(12+10*sin(a/5)));
		_cprintf("%c\0",(unsigned char)219); //fixed instead alt+219 to type extended ascii character 219
		a+=0.1;
	}while(a<=40);
}
void calce(void){
	unsigned long fact(unsigned int);
	double s,l;
	double x=POW_OF_e;
	unsigned int n=1;
	l=1;
	s=1;
	while(l>(10e-6)){
		l=pow(x,n) / fact(n++);
		s+=l;
	}
	printf("\r\ne = %f\r\n\0",s);
}
void infinitefunc(void){
	double s,n;
	_clrscr();
	printf("Enter N:\0");
	scanf("%lf",&n);
	s=sqrt(n);
	do{
		s=sqrt(s+n);
	}while(fabs(s-sqrt(s+n))>=10e-10);
	printf("Result = %f\r\n\0",s);
}
void modtriangle(void){
	unsigned int i,j;
	_clrscr();
	for(i=1;i<=15;i++){
		_gotoxy(40-i,i+5);
		for(j=i;j<=2*i-1;j++){
			printf("%d \0",j % 10);
		}
		for(j=2*i-2;j>=i;j--){
			printf("%d \0",j % 10);
		}
	}
}

void coins(void){
	unsigned long x2,x5,x10,x20,x50,s;
	int counter=0;
	_clrscr();
	for(x2=0;x2<=50;x2++)
		for(x5=0;x5<=20;x5++)
			for(x10=0;x10<=10;x10++)
				for(x20=0;x20<=10;x20++)
					for(x50=0;x50<=2;x50++){
						s=x2*2+x5*5+x10*10+x20*20+x50*50;
						if(s==100){
							printf("2 Unit = %lu, 5 Unit = %lu, 10 Unit = %lu, 20 Unit = %lu, 50 Unit = %lu \r\n\0",x2,x5,x10,x20,x50);
							counter++;
						}
						else{
							s=0;
						}
					}
	printf("Number of items: %d",counter);
}