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EXQ1:
Numerical Methods 2014/2015 - Example Tripos Question. Time allowed 30 minutes.
a) Sketch code for an ASCII to integer base conversion function
for base 10 (decimal) with the additional feature that any numbers
starting with a leading zero are handled in base 8 (octal).
[4 Marks]
b) Sketch code for the multiplication of fixed-point, signed numbers that
use 16 bits where the unit in the last place (ULP) is equal to 1/256.
Explain your encoding of polarity (the sign bit) and justify your decision.
[6 Marks]
c) One means for finding a value for Pi/4 is to compute
sufficient terms of the following expansion:
arctan x = x - x^3/3 + x^5/5 - x^7/7 + ...
i) Sketch the required code. Note, x will not need to appear in your code. [3 Marks ]
ii) Approximately how many terms will you need to sum for an answer accurate to one
part per million? Will underflow potentially affect your result ? How can this be minimised?
[5 Marks ]
d) Briefly compare the technique in part c) for finding a value of Pi with
Monte Carlo dart throwing and with potentially better ways. [2 Marks]
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