### BIO-SAVART LAW

/*A C code that returns the magnetic field at a mesh of points
*on the xy-plane (xp,yp) for a straight wire segment through which
*current passes. The total magnetic field used in this code
*has the form (cos(theta1)-cos(theha2))/(yp*r_mag)
*ignoring the constants permeability, pi and current I and
*taking them together as 1. Thus no need for trapezoid since
*the integral of Bio-Savart can be tractable!!!
*r_mag represents the distance between the dl segment and
*the point (xp,yp) where we will find the B*/
#include <stdio.h>
#include <math.h>
/*Global constant*/
#define L 3.0 /* length of the wire*/
double r_mag(double x, double xp, double yp) {
double rx;
rx=xp-x; /* x is any point on xprime*/
return sqrt(rx*rx+yp*yp);
}
main()
{ int i;
double xp,yp;
double B; /*the z component of mag-field that is total field.*/
FILE *fid;
fid=fopen("mag-field","w");
/*loop over xp and yp values*/
for (yp=-2.0;yp<=2.0;yp=yp+0.1)
for (xp=-1.5;xp<=1.5;xp=xp+0.1)
{ /* Form the function B*/
B=2*(xp-L/2)/(yp*r_mag(L/2,xp,yp));
fprintf(fid,"%10.6lf %10.6lf %10.6lf\n",xp,yp,B);
}
fclose(fid);
}

### QUANTUM CRYPTOGRAPHY HOMEWORK SOLUTIONS

Thank you Prof. Dr. İbrahim Yurdahan Güler

### NEWTON-RAPSON METHOD-8th degree Legendre polynomial

## Newton-Rapson Method to the smallest non negative root
## of the 8th degree Legendre Polynomial
## P8(x)=(1/128)(6435x^8-12012x^6+6930x^4-1260x^2+35)
## where -1<=x<=1.
## for the smallest non negative root, we can ignore
## all the terms except the last two by truncated
## the function to be zero and find
## x=0.167 as the initial smallest non negative
## root.
##Constants and initializations
x=[]; ## Empty array for the iterated x roots
x(1)=0.16700000; ## Initial guess to begin the iteration for the
## smallest non-negative root.
L8=[]; ## Empty array for the Legendre polynomial
L8p=[]; ## Empty array for the derivative of the Legendre polynomial
for i=1:100
##The value of the function at x
L8(i)=(1/128)*(6435*x(i)^8-12012*x(i)^6+6930*x(i)^4-1260*x(i)^2+35);
##The value of the derivative of the function at x
L8p(i)=(1/128)*(6435*8*x(i)^7-12012*6*x(i)^5+6930*4*x(i)^3-1260*2*x(i));
x(i+1)=x(i)-L8(i)/L8p(i); ## the iteration
endfor
## For plot let's define a new variable…

### Second Harmonic Generation

gnuplot> set xrange [-180:180] gnuplot> set yrange [-180:180] gnuplot> set pm3d gnuplot> set hidden3d  gnuplot> set title 'SHG' gnuplot> splot sin(cos(x*pi/180))*sin(cos(x*pi/180))/(cos(x*pi/180)*cos(x*pi/180))*sin(cos(y*pi/180))*sin(cos(y*pi/180))/(cos(y*pi/180)*cos(y*pi/180)) title 'N=1
'