Decimal fractions

[alhoop]

Is it possible to use a number like Pi or 9.17 as a constant on one of the M processors?
Thanks
Al

 

[Andrew Cowan]

No, integers only.

However, by multiplying by 100 (then dividing by 100 at the end (either by rounding or splitting up the number into parts), 9.17 can be represented (as 917).

 

[westaust55]

to expand upon the information provided by andrew,

if you have a constant 9.17

then use 917

so you might have

w1 = b0 * 917

then the whole part is

w1/100

the fraction is

w1 // 100


if you only want to print out the result then read up on the BINTOASCII command

either way you can then print the whole part, a period (".") and then the decimal fractional part

 

[bgrabowski]

And 355/113 is an astonishingly good approximation to Pi.

 

[BeanieBots]

And 355/113 is an astonishingly good approximation to Pi.

Thanks. Never knew that one. Very close indeed.

Not so good but easier to code without overflow is 22/7.

 

[westaust55]

Thanks. Never knew that one. Very close indeed.

Not so good but easier to code without overflow is 22/7.

Overflow is very certainly a consideration.

whether using byte or word variables, 65,535 is the largest number that can be handled internally (16-bit).

While 355 can be a constant to avoid using a word variable, to avoid overflow with simple maths, the largest number you can have prior to multiplying by 355 is 186.

Whereas with the well known 22/7 approximation you can have a value up to 29,797 before multiplying with 22 and not end up with overflow.