What is the Fixed-Point function replacement for atan?

I am converting my matlab function to vhdl. What is the function replacement for atan so that it can be converted to fixed point? And also another error is reported. error : Undefined function or variable 'epsilon_out'. The first assignent to a local variable determines its class. how to remove this.

Answer 1

[Tim McBrayer]

The list of functions supported for HDL code generation is in the HDL Coder documentation. As you have discovered, atan and atan2 are not supported. If you know your input range you can build a lookup table to approximate a function to a suitable precision.

The error message mentioning epsilonout is simply due to the presence of the earlier errors. Once you have valid implementations/replacements for atan and atan2, you won't encounter any issue with epsilonout.

[priya agarwal]

thank you. I'll try to build a lookup table.

[priya agarwal]

I made the lookup table in simulink. But how do I call this simulink block in my Matlab function?

Answer 2

[Bharath Venkataraman]

You can also try using cordicatan2, which gives you a CORDIC based inverse tangent value.

Answer 3

[Paul Bayendang]

1) Also figuring a work around for atan function

2) atan2 function is supported, as far as r2012a