Two problems

Hi, I am a beginner. I have three probs. 1) How to input the default angle in degrees rather than in radians?

2) I defined a as shown and calculated det(a)

a =

     1     2     3
     4     5     6
     7     8     9

>> det(a)

ans =

6.6613e-016

The ans should be zero but the output is a value very close to zero. But I want a zero. How do I do that?

3) How do I learn MATLAB? Should I read some book or should I just go through the help section one article after another?

Answer 1

[Evgeny Pr]

Hi!

1) Use functions: SIND, COSD, TAND, etc... and convertors RAD2DEG, DEG2RAD.

2) You can use FIX(DET(a)) :)

3) Book - it is always helpful . The more sources of information - the better. :)

[Rebeca link]

Thanks was useful to me¡

Answer 2

[Paulo Silva]

1) Matlab functions like sin and others only use radians, you can do the conversion

radians=degrees*pi/180

2) That determinant gives me zero but your result might be a problem with the floating-point relative accuracy, you can round numbers in several ways like:

round(det(a))

floor(det(a))

or use

fprintf('%1.5f',det(a)) %1 is the number of digits on the left and 5 is the number of digits on the right of the .

Your result is very close to the eps

eps  

doc eps

3)

linkexchange (books and articles)

blogs (tutorials)

fileexchange (lots of examples)

For new matlab/simulink users, do you know about the (interactive) video tutorials?!