只做了第4小题，放代码：
1 // <<DSP using MATLAB>>3rd edition 2 // Book Author:Vinay K Ingle, John G Proakis 3 // 4 // Problem 2.3(4) 5 // script by: 6 // 7 clear, clc, clf(); 8 9 mode(2); 10 funcprot(0); 11 exec(\'fun_banner.sci\'); // output version and OS info 12 //exec(\'fun_stepseq.sci\'); // unit step sequence 13 exec(\'fun_sigadd.sci\'); // sign sequence add/substract 14 15 // ------------------------------------------------------------------------ 16 // START Output Info about this sce-file 17 mprintf(\'\n***********************************************************\n\'); 18 [ban1,ban2] = fun_banner(); 19 mprintf("\n <DSP using MATLAB> 3rd edition, Problem 2.3(4) \n"); 20 mprintf(" ----------------------------------------------------------\n\n"); 21 22 // -----------END---------------------------------------------------------- 23 24 25 //%% 26 //%% {...,1,2,3,...} + {...,1,2,3,4,...} n=[0:24] 27 //%% * * 28 //%% what is the periods 29 30 self_length1 = 3; 31 periods1 = 8; 32 33 x1 = [1, 2, 3]; 34 n1 = [0:(2+(periods1-1) * self_length1)]; 35 xtilde1 = x1\' * ones(1,periods1); xtilde1 = (xtilde1(:))\'; 36 37 38 self_length2 = 4; 39 periods2 = 6; 40 41 n2 = [0:(3+(periods2-1) * self_length2)]; 42 x2 = [1, 2, 3, 4]; 43 xtilde2 = x2\' * ones(1,periods2); xtilde2 = (xtilde2(:))\'; 44 45 46 //% x = xtilde1 + xtilde2 47 [x,n] = fun_sigadd(xtilde1, n1, xtilde2, n2); 48 49 50 f0=scf(0); //creates figure with id==0 and make it the current one 51 // f.figure_size=[700,600]; // adjust window size 52 // f.background=2; // add background color 8-white 53 f0.figure_name="Problem 2.3(4)"; // name window 54 subplot(3, 1, 1); 55 plot(n1,xtilde1,\'bo\'); 56 plot(n1,xtilde1,\'b.\'); 57 plot2d3(n1,xtilde1,2); // Create plot with blue line 58 title("$Period\ Sequence\ \tilde{x_1}$",\'fontname\',7,\'fontsize\',4); 59 xlabel(\'n\',\'fontname\',3); ylabel(\'$\tilde{x_1}(n)$\',\'fontname\',3,\'fontsize\',3); 60 //xgrid(); 61 xgrid(5,0,7); // color, thickness, style 62 a0=get("current_axes"); // get the handle of the newly created axes 63 a0.data_bounds=[-0.1,24,-0.1,5]; 64 65 66 subplot(3, 1, 2); 67 plot(n2,xtilde2,\'bo\'); 68 plot(n2,xtilde2,\'b.\'); 69 plot2d3(n2,xtilde2,2); // Create plot with blue line 70 title("$Period\ Sequence\ \tilde{x_2}$",\'fontname\',7,\'fontsize\',4); 71 xlabel(\'n\',\'fontname\',3); ylabel(\'$\tilde{x_2}(n)$\',\'fontname\',3,\'fontsize\',3); 72 //xgrid(); 73 xgrid(5,1,7); // color, thickness, style 74 a1=get("current_axes"); // get the handle of the newly created axes 75 a1.data_bounds=[-0.1,24,-0.1,5]; 76 77 78 subplot(3, 1, 3); 79 plot(n,x,\'bo\'); 80 plot(n,x,\'b.\'); 81 plot2d3(n,x,2); // Create plot with blue line 82 title("$Period\ Sequence\ \tilde{x_1}+\tilde{x_2}$",\'fontname\',7,\'fontsize\',4); 83 xlabel(\'n\',\'fontname\',3); ylabel(\'x(n)\',\'fontname\',3); 84 //xgrid(); 85 xgrid(5,1,7); // color, thickness, style 86 a2=get("current_axes"); // get the handle of the newly created axes 87 a2.data_bounds=[-0.1,24,-0.1,8];
运行结果：
由上图可以看出，新序列的基本周期N=12。