PRACTICAL MATLAB® FOR ENGINEERS PRACTICAL MATLAB

434 Practical MATLAB® Applications for Engineers

figure(1)

ezplot(Is(1))

title(‘I1(s) vs s’)

xlabel(‘ complex frequency s ‘)

ylabel(‘I1(s) ‘)

ylabel(Amplitude’)

figure(2)

ezplot(Is(2))

title(‘I2(s) vs s’);

xlabel(‘complex frequency s’);

ylabel(‘Amplitude’)

disp(‘***************************************************’)

disp(‘******************* RESULTS **********************’)

disp(‘***************************************************’)

disp(‘The loop currents i1(t) and i2(t) (in amps) are: ‘)

disp(‘i1(t)=’),pretty(it(1))

disp(‘i2(t)=’),pretty(it(2))

disp(‘****************************************************’)

The script fi le IC_loop_diff_eqs is executed and the results are as follows (Figures 4.79

and 4.80):

>> IC _ loop _ diff _ eqs

**************************************************

**************** RESULTS ************************

**************************************************

The loop currents I1(s) and I2(s) are:

/ 15 \

2 / 47 \ (2 + 3 s) s |- 1/s - 9 - ------ |

(3 s + 7 s + 5) s |---- + 2 | | 2 |

\ s / \ s + 9 /

I1(s) = ------------------------------- + --------------------------------

4 3 4 3 2

3 s + 22 s + 37 s + 27 s + 6 3 s + 22 s + 37 s + 27 s + 6

2 / 15 \

/ 47 \ (s + 5 s + 2) s |- 1/s - 9 - ------ |

(2 + 3 s) s |---- + 2 | | 2 |

\ s / \ s + 9 /

I2(s) = ------------------------------- + ----------------------------------

4 3 2 4 3 2

3 s + 22 s + 37 s + 27 s + 6 3 s + 22 s + 37 s + 27 s + 6

***************************************************

The values of the currents (in amps) i1(0) and i2(0), and

i1(t=inf) and i2(t=inf) using the initial and final value theorems

are verified below:

i1 _ 0 = 2

i2 _ 0 = -3

i1 _ inf = 0

i2 _ inf = 0