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| Polar form of a Complex number |
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| Let z = x+iy denote the point P(x,y) in the xy plane. |
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| Then from the figure, we have |
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| z = r{cosq+isinq} is called the polar form of the complex number. |
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x + iy (which is in the cartesian form)
where  is called the modulus
of the complex number z denoted by |z| and q = tan-1 y/x is called the amplitude or argument of the complex
number z denoted by amp(z) or arg(z). |
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| The value of q
is such that -p < q £ p,
is called the principal value of the amplitude. |
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| The general value of the amplitude is q + 2np, where n is positive or negative integer and is the principal value of the amplitude. |
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| To find the principal value of
(amplitude) from the equation cos q = x/r and sin q
= y/r, the following table is useful. |
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