Discover MakerZone

MATLAB and Simulink resources for Arduino, LEGO, and Raspberry Pi

Learn more

Discover what MATLAB® can do for your career.

Opportunities for recent engineering grads.

Apply Today

Function is not defined for values of class embedded.fi when using HDL coder

Asked by Sam on 2 Apr 2013

Hi,

When I am experimenting in converting matlab code into vhdl with hdl coder, I am getting the error such as Function 'log' is not defined for values of class 'embedded.fi' or Function 'exp' is not defined for values of class 'embedded.fi'.

The specific block of code comes from the block:

        f_0 = fi( 0, 0, 1, 0, fm );  % 133.33333;
        f_sp = fi( 200*fi( 1/3, 0, 14, 15 ), 0, 14, 7, fm );  % 66.66667;
        brkfrq = fi( 1000, 0, 11, 0, fm );
        brkpt = fi( fi_div( (brkfrq - f_0), f_sp ), 0, 14, 10, fm );
        logstep = fi( 1.0711703, 0, 14, 13, fm );  
        linpts = (f<brkfrq);
        z = fi( fi( 0, 0, 1, 0 )*f, 0, 6, 0, fm );
        z( linpts ) = fi( fi_div( (f( linpts ) - f_0), f_sp ), 0, 6, 0, fm );
        % error with line below.
        z( ~(linpts~=0) ) = fi( brkpt + (log( fi_div( f( ~(linpts~=0) ), brkfrq ) )) ./ log( logstep ), 0, 6, 0, fm );

The original matlab code is from audspec.m of rastamat. I have tried converting fixed point to double before calling log(), but then another error pops up.

Thanks,

0 Comments

Sam

Products

1 Answer

Answer by Tim McBrayer on 2 Apr 2013
Accepted answer

As the error message states, there is no fixed-point version of the 'log' or 'exp' commands in MATLAB HDL Coder. The complete list of functions that have fixed point versions and are supported for HDL code generation is at http://www.mathworks.com/help/hdlcoder/ug/fixed-point-run-time-library-support.html.

1 Comment

Sam on 2 Apr 2013

Thanks for point this out. I think I was looking for that page, but couldn't find it.

Tim McBrayer

Contact us