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I am currently working towards a PhD in microbial genetics. Before that I spent a bit over a decade working as a programmer, with most of that time spent writing computer games. I have degrees in Mathematics (MMath), Life Sciences (BSc) and Molecular Genetics (MSc).


Sep
24
awarded  Autobiographer
Jun
30
comment Subtraction of a negative number
Not sure why this got downvoted, I think it cuts to the chase rather neatly.
May
20
awarded  Peer Pressure
May
19
awarded  Editor
Apr
28
comment A function such that $f(f(n)) = -n$?
Signed integers are not actually stored with a sign bit on any modern computer. Instead the MSB is treated as a negative value (a method called Two's complement). This gives much easier implementation of basic arithmetic and has only one representation of zero.
Apr
28
comment A function such that $f(f(n)) = -n$?
@Seth: Numbers in computers are stored in Two's complement. 31-bits are as you would expect and the highest bit means $-2^{32}$. The method you describe is One's complement and it is not used as it gives two representations of zero.
Apr
28
comment A function such that $f(f(n)) = -n$?
@TomCollinge: I think you mean $[-2^{31}, 2^{31})$. The lowest representable number in 32-bit twos complement is -$2^{31}$ and the highest is $2^{31}-1$.
Jan
30
awarded  Yearling
Aug
21
answered math fallacy problem: $-1= (-1)^3 = (-1)^{6/2} = \sqrt{(-1)^6}= 1$?
Aug
6
comment What would have been our number system if humans had more than 10 fingers? Try to solve this puzzle.
The next interesting question is: what we can we conclude from this information about Martians? The first natural conclusion is that Martians cannot be symmetrical about any number of axes other than thirteen- since 13 is prime - unless, that is, they have a single fingered appendage, which would have to be located along the axis of symmetry.
May
3
awarded  Critic
Apr
14
awarded  Nice Answer
Apr
5
awarded  Teacher
Apr
5
answered There are no bearded men in the world - What goes wrong in this proof?
Mar
7
comment What was the first bit of mathematics that made you realize that math is beautiful? (For children's book)
What if I am 4?
Feb
20
comment Is it true that the book 'Calculate Primes' has found the pattern?
Looks like it's a version of the sieve: tysondw.blogspot.co.uk/2009/01/…
Jan
30
awarded  Supporter