Two problems

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Y Vineel
Y Vineel 2011-3-12
评论： Rebeca link 2017-2-28
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?

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回答（2 个）

Evgeny Pr
Evgeny Pr 2011-3-12
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. :)
Paulo Silva
Paulo Silva 2011-3-12
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?!

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