From Scientific Calculator [Solve] to matlab
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Hi all, with my scientific calculator I could try something as the following
SHIFT+CLR(9) >> (3)>>Reset All >>[=] Reset All >> Press [AC]
-Set the calculator on the right limits:
sin(30)=1/2
sin(x) = 1/2 and solve for x [SHIFT] [SOLVE] [=] = 30
or
cos(X)^2*cos(3X)^2 = 0.5 and then SHIFT>>SOLVE
How I can implement something like that in matlab (especially for the second function at the bottom? How I can implement this solve functionality in matlab? I would like to thank you in advance for your help
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Answers (4)
Mischa Kim
on 24 Oct 2017
Edited: Mischa Kim
on 24 Oct 2017
Alex, use something like
fun = @(X) cos(X)^2*cos(3*X)^2 - 0.5;
options = optimoptions('fsolve','Display','none','PlotFcn',@optimplotfirstorderopt);
sol = fsolve(fun,0,options)
The options command is not required but shows you some of the capabilities of MATLAB.
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Torsten
on 24 Oct 2017
syms x
eqn = cos(x)^2*cos(3*x)^2-0.5 == 0;
sol = solve(eqn)
or
syms x
eqn = cos(x)^2*cos(3*x)^2-0.5 == 0;
sol = vpasolve(eqn)
Best wishes
Torsten.
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Steven Lord
on 24 Oct 2017
Since this is one equation in one unknown, you can use fzero to solve this.
>> f = @(x) cos(x)*cos(3*x)-0.5707;
>> result = fzero(f, 0);
>> check = f(result)
check =
0
However, it appears your calculator computes the cosine of angles in degrees. The cos function in MATLAB computes the cosine of an angle in radians. To compute the cosine of an angle in degrees in MATLAB, use the cosd function instead of cos.
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