## Fast fixed point pow, log, exp and sqrt

I’ve got a fixed point class (10.22) and I have a need of a pow, a sqrt, an exp and a log function.

Alas I have no idea where to even start on this. Can anyone provide me with some links to useful …

## Invert 4×4 matrix – Numerical most stable solution needed

I want to invert a 4×4 matrix. My numbers are stored in fixed-point format (1.15.16 to be exact).

With floating-point arithmetic I usually just build the adjoint matrix and divide by the determinant (…

## How to use expr on float?

I know it’s really stupid question, but I don’t know how to do this in bash:

20 / 30 * 100
It should be 66.67 but expr is saying 0, because it doesn’t support float.
What command in Linux can …

## Why does GHC make fix so confounding?

Looking at the GHC source code I can see that the definition for fix is:

fix :: (a -> a) -> a
fix f = let x = f x in x
In an example fix is used like this:

fix (\f x -> let x’ = x+1 in x:f …

## How to make use of the GCC fixed-point types extension on ARM Cortex-M?

I am using a ARM Cortex-M3, and a Cortex-M4. I want to make use of GCC’s fixed-point type extension. I am using the summon-arm-toolchain. The following line of code

_Fract f = 0.1;
throws the …

## Python computing error

I’m using the API mpmath to compute the following sum

Let us consider the serie u0, u1, u2 defined by:

u0 = 3/2 = 1,5

u1 = 5/3 = 1,6666666…

un+1 = 2003 – 6002/un + 4000/un un-1
The serie …

## Algorithm for fixed-point multiplication

I’m trying to rescale a timestamp (fractional part of seconds only) from nanoseconds (units of 10^-9 seconds) to the lower half of an NTP timestamp (units of 2^-32 seconds). Effectively this means …