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How do i understand the output of a solve function?

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Mikkel
Mikkel on 20 May 2014
Commented: Mikkel on 9 Jun 2014
Hi I have solved two equations and now I would like to calculate/simplify the results, before I turn them from rad's to deg's. But somehow I wont allow me to. My code (so far) looks like this:
syms x
eta = ((30+42)/2)*(pi/180);
gamma = 2*pi/3;
X = solve(1*cos(gamma-eta)-1.2*cos(x-eta),x)
Y = solve(1*sin(gamma-eta)-1.2*sin(x-eta),x)
My results then become
X =
pi/5 + acos(12553449285915085/144115188075855872)
pi/5 - acos(12553449285915085/144115188075855872)
Y =
pi/5 + asin(22394642186961775/27021597764222976)
(6*pi)/5 - asin(22394642186961775/27021597764222976)
what I would like to do is simmelar to
>> pi/5 + acos(12553449285915085/144115188075855872)
ans =
2.1119
>> radtodeg(ans)
ans =
121.0028
But this I can only do from the command window, How do I do this from my code?

  2 Comments

Star Strider
Star Strider on 20 May 2014
The obvious suggestion is for you to post the relevant parts of your script ‘.m’ file.
What errors or unexpected results do you get when those commands are part of your script file?
Mikkel
Mikkel on 9 Jun 2014
The unexpected result would be that of the secound section with code.. and what I would like was the theerd code section. But I found that a simple eval(solve(...)) solved my problem.

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Accepted Answer

Mischa Kim
Mischa Kim on 21 May 2014
Mikkel, use
X = vpa(solve(1*cos(gamma-eta)-1.2*cos(x-eta),x))
Y = vpa(solve(1*sin(gamma-eta)-1.2*sin(x-eta),x))
instead.

  1 Comment

Mikkel
Mikkel on 9 Jun 2014
This seemed to give me the same result. But a eval(solve(...)) gave me the expresion in the form that I was looking for

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