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How to reduce decimal places displayed in symbolic matrix?

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Ali
Ali 2022-12-9
评论： Walter Roberson 2022-12-10
Hi, I have a matrix which contains symbolic elements. I'd like to decrease decimal count display to enhance readability.
Here is my matrix. I just copied the output of an attempt, please ignore the vpa.
syms t Omega
eta(Omega) = [(vpa("8000.0")*cos(Omega*t + vpa("0.78539816339744830961566084581988"))*(vpa("26838195793182970854745861920038.0")*Omega^2 - vpa("2.4154462400944206989319304935157e+34")))/(vpa("4.153837486827862102824397063376e+34")*Omega^4 - vpa("3.7425286527196553136998040116897e+37")*Omega^2 + vpa("3.6554306435273366948203088051441e+37")); -(vpa("0.0152587890625")*cos(Omega*t + vpa("0.78539816339744830961566084581988"))*(vpa("9.7133610940578263277504767935649e+35")*Omega^2 - vpa("9.4976141444561753442642817416859e+35")))/(vpa("4.153837486827862102824397063376e+34")*Omega^4 - vpa("3.7425286527196553136998040116897e+37")*Omega^2 + vpa("3.6554306435273366948203088051441e+37"))]
format short
does NOT help. I believe it's because the matrix has symbolic elements.

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采纳的回答

Walter Roberson
Walter Roberson 2022-12-9
vpa(eta, DIGITS)
Note that exponents might not be affected in some cases
  2 个评论
Ali
Ali 2022-12-10
Hi, thanks for your answer. Unfortunately, this doesn't work when assigning to a symbolic function.
>> q_hat(Omega) = vpa(q_hat(Omega),3)
q_hat(Omega) =
(27746.870093822479248046875 + 27746.870093822479248046875i)/(1000000.0*Omega^4 - 900981000.0*Omega^2 + 880012917.0)
-(0.0000000000000022737367544302526432562150870628*(Omega^2*(6219777023972212736.0 + 6219777023972212736.0i) - 5591697720268541657088.0 - 5591697720268541657088.0i))/(1000000.0*Omega^4 - 900981000.0*Omega^2 + 880012917.0)
>> q_hat = vpa(q_hat(Omega),3)
q_hat =
(2.77e+4 + 2.77e+4i)/(1.0e+6*Omega^4 - 9.01e+8*Omega^2 + 8.8e+8)
-(2.27e-15*(Omega^2*(6.22e+18 + 6.22e+18i) - 5.59e+21 - 5.59e+21i))/(1.0e+6*Omega^4 - 9.01e+8*Omega^2 + 8.8e+8)
>>
Walter Roberson
Walter Roberson 2022-12-10
Ran in:
It looks to me as if at the time you create a symbolic function using the notation of symbolic subscript on the left-hand side, it looks at the current digits setting and locks that in to the function.
However, if the right hand side of the expression is a symbolic function and you do not use the symbolic variable subscript on the left hand side, it does not do that.
syms x
f(x) = sym('0.0000000000000022737367544302526432562150870628')*x
f(x) = 
g(x) = vpa(f,3)
g(x) = 
h = vpa(f,3)
h(x) = 
digits(5)
h(x) = vpa(f,3)
h(x) = 

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