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Taking derivative along the radial line....
Posted Apr 24, 2015, 10:35 p.m. EDT Version 4.4 2 Replies
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Hi, I am working on the fault diagnosis of the substation grounding grid. I want to calculate the derivative of magnetic flux density along the radial line...Could anyone help how to take this derivative. Like we have x and y-axis if i draw a line y=x and then take derivative with respect to that line. What i did is r=sqrt(x^2+y^2) and the find d/dr but this is wrong......
2 Replies Last Post Apr 26, 2015, 12:03 a.m. EDT
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Posted:
10 years ago
Right -- you need to know what direction you want. So if I define c = the cosine of an angle around the origin and s is the sine of the angle, then you want:
d/dr = d/dx ∂x/∂r + d/dy ∂y/∂r
by the chain rule, where r is along a radial direction.
But ∂x/∂r = c, and ∂y/∂r = s, so then you get:
d/dr = c d/dx + s d/dy
That's it. No squares or square roots.
d/dr = d/dx ∂x/∂r + d/dy ∂y/∂r
by the chain rule, where r is along a radial direction.
But ∂x/∂r = c, and ∂y/∂r = s, so then you get:
d/dr = c d/dx + s d/dy
That's it. No squares or square roots.
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Posted:
10 years ago
Thanks Daniel, I got your point so in this case derivative with respect to phi will be:
d/dphi=-r*s(phi)*d/dx + r*c(phi)*d/dy....
right?
d/dphi=-r*s(phi)*d/dx + r*c(phi)*d/dy....
right?