Debugging with the help of Editor/Debugger

One of means of tool search of mistakes is application of the built - in system of editing and debugging of programs by name Editor/Debugger.

Let’s familiarize with Editor/Debugger options with help an example of program Circuit1_debug.

Before the session will be begun, it is expedient to clear Workspace with the help of command Clear and Command Window with the help of command Clc entered in Command Window (it is possible to use Main menu EditClear Workspace and Main menuEditClear Command Window with this purpose).

 Start debugger of programs. For this purpose press Main menuDebugRun. After that, pointing out the cursor to any variable or an array in the text of the program, it is possible to look after their numerical (or symbolical) values.

 Clear Workspace and Command Window. Stand up the cursor before any operator. Let it be the operator in a line 13

XL=2*pi*f*L2;

Press icon Set/clear breakpoint on panels of tools. The red point from the left of the specified operator designates a point of interruption of the program running. Press DebugRun. The green arrow appeared in the text of the program points out to the operator before that calculations are stopped. In Command Window you will see the invitation

K> >

to enter the further instructions. Before you will make it, bring the cursor to values of the variables calculated before interruption. The system will show these values. However, you cannot view values of variables and arrays after point of interruption, as they are not determined yet.

 Press icon Step on panels of tools. The green arrow will be moved for one line downwards. The program has executed one operator and has again stopped. Thus, it is possible to carry out the program step by step, supervising both a sequence of calculations and values of the calculated variables and arrays. Finish up to the end performance of the program, using step-by-step calculation. Observe change and appearance of the new information.

 Start the program again (press DebugRun). To execute the program to nearly up after interruption, press button Continue on panel of tools. You will see results of calculations in Command Window.

 By means of button Set/clear breakpoint, it is possible to remove the point of interruption shown by cursor. By means of button Clear all breakpoints, it is possible to remove all points of interruption in the program.

 To come in the subroutine using step-by-step debugging call M – file by name Circuit 3 from the editor of programs. Save it in the same directory as Circuit 3_debug. Purposely of economy of time, we shall replace operators of dialogue entering by awarding operators (use for this purpose operators of input of M - file Circuit 1).

 The program should look as follows:

% THE EXAMPLE OF CALCULATION OF THE SINE WAVE

CURRENT CIRCUIT

% Circuit 3_debug

f=50;

R1=1;

R2=2;

R3=3;

L2=1e-3;

C3=1e-4;

ph1=30;

ph2=60;

XL=2*pi*f*L2;

XC=1 / (2*pi*f*C3);

E1=100/sqrt (2) *exp (ph1*pi/180*i);

E2=200/sqrt (2) *exp (ph2*pi/180*i);

Z1=R1; Z2=R2+i*XL; Z3=R3-i*XC;

M = [1 -1 -1;

Z1 0 Z3;

0 Z2 -Z3];

F = [0; E1; -E2];

I=M\F;

disp ([' I1 = ', num2str (I (1,1))]);

disp ([' I2 = ', num2str (I (2,1))]);

disp ([' I3 = ', num2str (I (3,1))]);

% Check up according to 2-nd Kirchhoff’s rule

eps=E1-E2-Z1*I (1,1)-Z2*I (2,1);

disp ([' error calculation eps = ', num2str (eps)]);

% Calculation modules and arguments (radians) of the calculated currents

I1M=abs (I (1,1));

I2M=abs (I (2,1));

I3M=abs (I (3,1));

phI1=angle (I (1,1));

phI2=angle (I (2,1));

phI3=angle (I (3,1));

disp ([' I1M = ', num2str (I1M), ' phI1 = ', num2str (phI1/pi*180)]);

disp ([' I2M = ', num2str (I2M), ' phI2 = ', num2str (phI2/pi*180)]);

disp ([' I3M = ', num2str (I3M), ' phI3 = ', num2str (phI3/pi*180)]);

% GRAPH

h=0.04/200;

t (1)= 0;

i1 (1) =current (I1M, f, phI1, t (1));

i2 (1) =current (I2M, f, phI2, t (1));

i3 (1) =current (I3M, f, phI3, t (1));

for k=2:201

t (k) =t (k-1) +h;

i1 (k) =current (I1M, f, phI1, t (k));

i2 (k) =current (I2M, f, phI2, t (k));

i3 (k) =current (I3M, f, phI3, t (k));

end

plot (t, i1, t, i2, t, i3);

 To investigate operation of the program by a cycle, as a rule, it is enough to do 2 - 3 entries in it. Therefore, replace the top limit of the operator of a cycle as follows

for k=2:5

t (k) =t (k-1) +h;

i1 (k) =current (I1M, f, phI1, t (k));

i2 (k) =current (I2M, f, phI2, t (k));

i3 (k) =current (I3M, f, phI3, t (k));

end

 Save the changed program.

 Stand up cursor before the operator of definition of a time step of calculation of values of branch current functions.

h=0.04/200;

Also, set up a breakpoint.

 For the control of performance of subroutines, take advantage of option Step in on the panel of tools, that enables to look after step-by-step performance of subroutine operators. Execute the program up to the end with the help of this option.

 Option Step out allows to leave the subroutine at any stage of its running.

 Option Exit Debug Mode realizes an exit from a mode of debugging.

From Main menu Breakpoints menu, it is possible to click additional options of debugging:

 Stop If Error – stop of the program in case of a mistake;

 Stop If Warning – stop of the program in case of the system warning of a probable mistake;

 Stop If NaN Or Inf - stop of a case not numerical or infinite value of calculated value.

Application of those or different ways and options of debugging of programs is determined by the programmer himself according to his experience, qualification, a complexity of a solved problem and individual style of programming.