math library on msp430

[voelker 10]

Hi all,

 

for one of my project i need to use sin, cos, sqrt, atan2 functions from the math library. When i'am using atan2 function, everything goes fine, but when i try to use sin, cos or sqrt, the compiler says it cannot allocate the bss segement (ram). Does any of you know an alternative to the math library with a small footprint ? I have implemented sin, cos and sqrt my way, but cos and sin seems to suffer from precision problems (taylors series).

 

Thanks

[bluehash 1,581]

There is an optimized sine code in the StellarisWare library.

Look in the /Utils folder. There will be a sine.c file

[voelker 10]

Thanks for the link, i'am gonna check it.

i'am using these functions to cimpute distance between too set of gps coordinates. The distance computation is fine for long distance but for short distance, the function underestimate the distance. For example for a 8.6km distance i get 5.6km. The point is that for a short distance like 600m i get 480m ... it seems that the error is not linear or happens for some specific values. This precision is sufficient for my application but i'd like to understand the problem.

[rockets4kids 204]

Are you looking for a small RAM footprint, ROM, footprint, or CPU cycle footprint?

 

Just how much precision do you need?

 

In resource-limited MCUs, table-based lookups and approximation are commonly used to meet precision requirements with minimal resources.

[voelker 10]

Hi,

 

i have more cpu cycles and rom space than i need, so i'am looking for something that fits the value line ram.

[voelker 10]

i found my problem, and the problem is ... me ! I used haversine function on angle in degree decimal-minute while it should take angle in decimal degree ... Everything is working fine and my implementation gives an error of ~10m compared to an implementation using math.h with double type.