◄Summary►  ◄Timings►
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Partial Tangent
 
Syntax:  FPTAN
 
Finds the partial tangent by calculating Y / X = TAN(Z). Z is taken from
ST. Z must be in the range 0 ≤ Z ≤ π / 4 on the 8087 and 80287. On the
80387, |Z| must be less than 2^63. The result is the ratio Y / X. Y
replaces Z, and X is pushed into ST. Thus Y is returned in ST(1) and X
in ST.
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