Monday, May 11, 2009
Sequence & Series Formulas
Arithmatic Progression
a,a+d,a+2d...., a+nd
- nth term of arithmatic progression
Tn = a + (n-1) d
- Sum of n - terms of arithmatic progression
Sn= (n/2) [ 2a + (n - 1) d]
- if a,b and c are in arithmatic progression then b = (a + c)/2.
a,ar,ar^2,..., ar^n
- nth term of geomatric progression is given by Tn = a r^(n-1).
- Sum of the first n terms of geomatric progression is given by;
Sn = a [ (1 - r^n) / (1 - r) ] , for r<1>
Sn = a [ (r^n - 1)/ (r - 1) ], for r>1
- if three quantities a,b and c are in GM then b = Sqrt(ac);
- Infinite Geomatric Series
when |r|<1
S* = a / (1 - r);
when |r|>1 then
S*= Infinity;
Harmonic Mean
- HM of a and b is 2ab/(a+b).
- nth terms of Harmonic Progression is Tn = 1 / [ a + (n-1) d ]
- Sum of first n - natural number is given by: summation (r=1 to n) : n (n + 1) / 2.
- Sum of squares of first n - natural number is given by summation (r=1 to n) :[ n ( n + 1 ) (2n + 1) ] / 6
- Sum of cubes of first n - natural number is given by summation (r=1 to n) : [n^2 (n+1)^2 ]
/4.
Sunday, May 10, 2009
Paging Program
Paging Related C Program:
Input : 45
Output : 10 + 10 + 10 + 10 + 5
#include
#include
void main()
{
int numberoflinksperpage=10;
int n,low,high,i=0;
clrscr();
printf("Enter number : ");
scanf("%d",&n);
while(n>numberoflinksperpage)
{
low=i;
high=i+1;
i++;
printf("\n display results from %d to %d ",numberoflinksperpage*low,numberoflinksperpage*high);
n=n-numberoflinksperpage;
}
low=i;
high=i+1;
printf("\n display results from %d to %d ",numberoflinksperpage*low,numberoflinksperpage*(high-1)+n);
getch();
}
Wednesday, April 29, 2009
Decimal to Binary
Input : any Decimal Number
Output : Binary format
Logic:
1) Take any natural number say..10.
2) divide by 2, and find remainder...repeat the same process until u get 0.
divisor number remainder
2 10 (0)
---------------------------------
2 5 (1)
----------------------------------
2 2 (0)
----------------------------------
2 1 (1)
----------------------------------
0
3) Now look at the remainder pattern from bottom to top, ie. 1010 which is an equivallent for decimal number 10.
Sunday, April 26, 2009
Combination of Strings
Input : Any number of Strings
Output : Combinations of Strings
for eg: A,B,C(input)
then Output :
A
B
C
AB
AC
AC
AD
BC
BD
CD
ABC
mathematical formula : nCr = n ! / (n-r) ! r !
Algorithm with explanations:
1) Enter the number of strings.
Let say 3. A,B and C.
2) now loop from i=1 to 2^3-1 = 7 (in general (2^n) -1 ).
3) Observe binary patterns for each of the numbers coming in that loop.
like in the following case.
Number Bianry Pattern
(A) (B) (C)
1 0 0 1
2 0 1 0
3 0 1 1
4 1 0 0
5 1 0 1
6 1 1 0
7 1 1 1
4) now put the appropriate string where 1 appears, and put nothing in case of 0.
ie.
1st entry becomes C
2nd entry B
3 BC
4 A
5 AC
6 AB
7 ABC
Thats all u need.
Thanks
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