how to differentiate this equation

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areej abdulshaheed
编辑： KALYAN ACHARJYA 2020-3-2
if I have this equation
theta=-2*alpha*sin(kn*pi/n)*sin(2*kn*pi*s/L+2*kn*pi*(i)/n+kn*pi/n)
how can I differenat theta(s) to theta_D and theta_DD

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回答（1 个）

KALYAN ACHARJYA
KALYAN ACHARJYA 2020-3-2
编辑：KALYAN ACHARJYA 2020-3-2
syms s
theta_D=diff(theta,s);
theta_2D=diff(theta,s,2); %or theta_2D=diff(theta_D,s);
diff
  2 个评论
areej abdulshaheed
areej abdulshaheed 2020-3-2
this erroer occur
Error using diff
Difference order N must be a positive integer scalar.
Error in mohammed (line 43)
theta_D=diff(theta,s)
Walter Roberson
Walter Roberson 2020-3-2
diff() can only be used to differentiate symbolic expressions or symbolic functions. If you attempt to differentiate a numeric array but pass in a symbolic variable as the second parameter, or pass in anything that is not a scalar integer (such as a vector of numeric values), then you would get that error.

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