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+{
+"cells": [
+ {
+		   "cell_type": "markdown",
+	   "metadata": {},
+	   "source": [
+       "# Chapter 8: Information theory"
+	   ]
+	},
+{
+		   "cell_type": "markdown",
+		   "metadata": {},
+		   "source": [
+			"## Example 8.10_A: SNR.sce"
+		   ]
+		  },
+  {
+"cell_type": "code",
+	   "execution_count": null,
+	   "metadata": {
+	    "collapsed": true
+	   },
+	   "outputs": [],
+"source": [
+"clc;\n",
+"clear;\n",
+"W=3000;\n",
+"SNR_db=39;// 10log (SNR_ratio)=SRN_db\n",
+"SNR_ratio=7943; //10^(3.9)\n",
+"\n",
+"C=W*log2(1+SNR_ratio);\n",
+"\n",
+"disp(C,'Capacity (in bits/s) =');"
+   ]
+   }
+,
+{
+		   "cell_type": "markdown",
+		   "metadata": {},
+		   "source": [
+			"## Example 8.1_A: Information_Rate.sce"
+		   ]
+		  },
+  {
+"cell_type": "code",
+	   "execution_count": null,
+	   "metadata": {
+	    "collapsed": true
+	   },
+	   "outputs": [],
+"source": [
+"clc;\n",
+"clear;\n",
+"p1=1/8;\n",
+"p2=1/8;\n",
+"p3=5/8;\n",
+"p4=1/8; //Quantization Levels\n",
+"//B is the Bandwidth of the signal\n",
+"\n",
+"H=p1*log2(1/p1)+p2*log2(1/p2)+p3*log2(1/p3)+p4*log2(1/p4);\n",
+"\n",
+"disp(H,'The average Information (in bits/message)=');\n",
+"disp('The Information Rate R=rH  =2*B(1.55) =3.1B bits/s');"
+   ]
+   }
+,
+{
+		   "cell_type": "markdown",
+		   "metadata": {},
+		   "source": [
+			"## Example 8.2_A: ShannonFano_and_Huffman_coding.sce"
+		   ]
+		  },
+  {
+"cell_type": "code",
+	   "execution_count": null,
+	   "metadata": {
+	    "collapsed": true
+	   },
+	   "outputs": [],
+"source": [
+"clc;\n",
+"clear;\n",
+"m1=0.2;\n",
+"m2=0.3;\n",
+"m3=0.2;\n",
+"m4=0.15;\n",
+"m5=0.15; // probability of 5 source messages \n",
+"\n",
+"H=m1*log2(1/m1)+m2*log2(1/m2)+m3*log2(1/m3)+m4*log2(1/m4)+m5*log2(1/m5);//Average information in bits\n",
+"\n",
+"//a) Shannon-fano coding\n",
+"                     //coding\n",
+"// m1  0.2  0 0         00\n",
+"// m2  0.3  0 1         01\n",
+"// m3  0.2  1 0         10\n",
+"// m4  0.15 1 1 0       110\n",
+"// m5  0.15 1 1 1       111\n",
+"\n",
+"L=(0.2*2)+(.3*2)+(0.2*2)+(2*0.15*3) //Average code word length(in bits)=probability *coding length\n",
+"\n",
+"n=H/L; \n",
+"\n",
+"disp(n*100,'Coding efficiency for Shannon Fano coding is');\n",
+"\n",
+"//b)  Huffman coding\n",
+"\n",
+"// m1 0.2     01\n",
+"// m2 0.3     00 \n",
+"// m3 0.2     11\n",
+"// m4 0.15    010\n",
+"// m5 0.15    110\n",
+"\n",
+"L=(0.2*2)+(.3*2)+(0.2*2)+(2*0.15*3) //Average code word length(in bits)=probability *coding length\n",
+"\n",
+"n=H/L;\n",
+"\n",
+"disp(n*100,'Coding efficiency for Huffman coding is');\n",
+"\n",
+"//change in answer due to rounded off value in text-book"
+   ]
+   }
+,
+{
+		   "cell_type": "markdown",
+		   "metadata": {},
+		   "source": [
+			"## Example 8.3_A: Gaussian_Channel.sce"
+		   ]
+		  },
+  {
+"cell_type": "code",
+	   "execution_count": null,
+	   "metadata": {
+	    "collapsed": true
+	   },
+	   "outputs": [],
+"source": [
+"clc;\n",
+"clear;\n",
+"\n",
+"PSD=10^(-9); //noise PSD in W/Hz\n",
+"Bw=4000;//Wandwidth in Hz\n",
+"\n",
+"//a) \n",
+"E=0.1 //Energy in Joules\n",
+"C=Bw*log2(1+E/(2*PSD*Bw));\n",
+"disp(C,'a) Capacity of the gaussian channel(in bits/s) when E is 0.1J=');\n",
+"\n",
+"//b) \n",
+"E=0.001 //Energy in Joules\n",
+"C=Bw*log2(1+E/(2*PSD*Bw));\n",
+"disp(C,'b) Capacity of the gaussian channel(in bits/s) when E is 0.001J=');\n",
+"\n",
+"//c)\n",
+"Bw=10000;\n",
+"C=Bw*log2(1+E/(2*PSD*Bw));\n",
+"disp(C,'d) Capacity of the gaussian channel(in bits/s) when Bw is 10Khz=');\n",
+"\n",
+"disp('100 times fall in Energy when the BW is increased by 2.5 times');"
+   ]
+   }
+,
+{
+		   "cell_type": "markdown",
+		   "metadata": {},
+		   "source": [
+			"## Example 8.5_A: Throughput_efficiency.sce"
+		   ]
+		  },
+  {
+"cell_type": "code",
+	   "execution_count": null,
+	   "metadata": {
+	    "collapsed": true
+	   },
+	   "outputs": [],
+"source": [
+"clc;\n",
+"clear;\n",
+"k=973;\n",
+"n=1023;\n",
+"Pa=0.99;\n",
+"Tw=10*10^(-6);\n",
+"Tl=40*10^(-6);\n",
+"N=4;\n",
+"\n",
+"N_sw=(k/n)*(Pa/(1+Tl/Tw));// efficiency of stop and wait algorithm\n",
+"N_sgpull=(k/n)*(1/(1+N*(1-Pa)/Pa));//efficiency of go-back-N algorithm\n",
+"Nsr=(k/n)*Pa;// efficiency of selective repeat algorithm\n",
+"\n",
+"disp(N_sw,'N s&w');\n",
+"disp(N_sgpull,'Nsgpull');\n",
+"disp(Nsr,'Nsr');"
+   ]
+   }
+,
+{
+		   "cell_type": "markdown",
+		   "metadata": {},
+		   "source": [
+			"## Example 8.6_A: Rate_of_source.sce"
+		   ]
+		  },
+  {
+"cell_type": "code",
+	   "execution_count": null,
+	   "metadata": {
+	    "collapsed": true
+	   },
+	   "outputs": [],
+"source": [
+"clc;\n",
+"clear;\n",
+"p1=1/2;\n",
+"p2=1/4;\n",
+"p3=1/8;\n",
+"p4=1/16;\n",
+"p5=1/16;// probabilities\n",
+"\n",
+"H=p1*log2(1/p1)+p2*log2(1/p2)+p3*log2(1/p3)+p4*log2(1/p4)+p5*log2(1/p5);\n",
+"Bw=4000; //Bandwidth in Hz\n",
+"R=2*H*Bw ;\n",
+"\n",
+"disp(R,'Rate of the source ( in bits/s) is');"
+   ]
+   }
+,
+{
+		   "cell_type": "markdown",
+		   "metadata": {},
+		   "source": [
+			"## Example 8.7_A: entropy_of_equiprobable_source.sce"
+		   ]
+		  },
+  {
+"cell_type": "code",
+	   "execution_count": null,
+	   "metadata": {
+	    "collapsed": true
+	   },
+	   "outputs": [],
+"source": [
+"clc;\n",
+"clear;\n",
+"\n",
+"// probability of all the events are same\n",
+"syms N;\n",
+"\n",
+"H_X=N*[(-1/N)*log(1/N)]; //H(X)=(-1/N)log(1/N)+(-1/N)log(1/N)+....N times\n",
+"\n",
+"disp(H_X,'H(X)=');"
+   ]
+   }
+,
+{
+		   "cell_type": "markdown",
+		   "metadata": {},
+		   "source": [
+			"## Example 8.8_A: Self_Information.sce"
+		   ]
+		  },
+  {
+"cell_type": "code",
+	   "execution_count": null,
+	   "metadata": {
+	    "collapsed": true
+	   },
+	   "outputs": [],
+"source": [
+"clc;\n",
+"clear;\n",
+"P0=2/3; //P(X=0)\n",
+"P1=2/3; //P(Y=0)\n",
+"H_x=0.919;\n",
+"H_y=0.919;\n",
+"H_b=0.919; //Hb(2/3)\n",
+"\n",
+"//since X,Y pair is uniformly distributed on  three values\n",
+"H_xy=log2(3); // H(X,Y)\n",
+"\n",
+"H_xdivy=H_xy-H_y; //H(X/Y)=H(X,Y)-H(Y)\n",
+"I_xdivy=H_x-H_xdivy; //I(X,Y)=H(X)-H(X/Y)\n",
+"\n",
+"disp(I_xdivy,'I(X,Y)=');\n",
+"\n",
+""
+   ]
+   }
+],
+"metadata": {
+		  "kernelspec": {
+		   "display_name": "Scilab",
+		   "language": "scilab",
+		   "name": "scilab"
+		  },
+		  "language_info": {
+		   "file_extension": ".sce",
+		   "help_links": [
+			{
+			 "text": "MetaKernel Magics",
+			 "url": "https://github.com/calysto/metakernel/blob/master/metakernel/magics/README.md"
+			}
+		   ],
+		   "mimetype": "text/x-octave",
+		   "name": "scilab",
+		   "version": "0.7.1"
+		  }
+		 },
+		 "nbformat": 4,
+		 "nbformat_minor": 0
+}