Fixed point coder log10 implementation

The function "log10" is supported for code generation in the latest version (R2020b) of MATLAB. You can find the list of supported functions in the below page :

https://www.mathworks.com/help/referencelist.html?type=function&capability=codegen

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Life is Wonderful 2020-11-19

Thanks - I see, is there a way I can use with R2019b ?

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Answer 3

Life is Wonderful 2020-11-20

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https://ww2.mathworks.cn/matlabcentral/answers/653293-fixed-point-coder-log10-implementation#answer_550623

在 MATLAB Online 中打开

I made a test and I don't see the expected result

I am still getting the error following error

??? Function 'log10' is not defined for values of class 'embedded.fi'.

My question - did you verify log10 ?

Below is  the matlab version   
>> ver
-----------------------------------------------------------------------------------------------------
MATLAB Version: 9.9.0.1524771 (R2020b) Update 2
MATLAB License Number: 40523231
Operating System: Microsoft Windows 10 Enterprise Version 10.0 (Build 18363)
Java Version: Java 1.8.0_202-b08 with Oracle Corporation Java HotSpot(TM) 64-Bit Server VM mixed mode
-----------------------------------------------------------------------------------------------------
MATLAB                                                Version 9.9         (R2020b)
Fixed-Point Designer                                  Version 7.1         (R2020b)
HDL Coder                                             Version 3.17        (R2020b)
HDL Verifier                                          Version 6.2         (R2020b)
MATLAB Coder                                          Version 5.1         (R2020b)
Parallel Computing Toolbox                            Version 7.3         (R2020b)

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Life is Wonderful 2020-11-20

编辑：Life is Wonderful 2020-11-20

在 MATLAB Online 中打开

i don't see you generating the Fix point matlab file ? For me - the problem is with coder app generating the fixpoint matlab script

Did you notice your C code still had double for nargin? You have to consider sign, WL and FL for your input and then feed to log10 . Another point for your notice - 20*log10 (x) is NOT fixed point-

Several compiler ask to log function as they won't include the log10 in math.h . For example of Linux based implementation.

Try following sequence

fixptcfg = coder.config('fixpt')
fixptcfg.TestBenchName = 'compute_log_tb';
cfg = coder.config('lib');
codegen -float2fixed fixptcfg -config cfg compute_log -args {3}
============= Step3: Generate Fixed Point Code ==============
### Generating Fixed Point MATLAB Code compute_log_fixpt using Proposed Types
### Generating Fixed Point MATLAB Design Wrapper compute_log_wrapper_fixpt
### Generating Mex file for ' compute_log_wrapper_fixpt '
??? Function 'log10' is not defined for values of class 'embedded.fi'.
Error in ==> compute_log_fixpt Line: 10 Column: 28
Code generation failed: View Error Report
Build failed.
Use help codegen for more information on using this command.

Life is Wonderful 2020-11-20

编辑：Life is Wonderful 2020-11-20

May I know what is the difference ?

Why No Fraction length ?

How did you arrive to the conclusion ?

what if y = 20*fi(log(double(x)),1,16,FL) is considerd ?if FL is 16- we get overflow but correct conversion value

Can please share the explanation in case of WL = 8,16,24,32,64- what should be the FL ?

What is range , slope , bias , resolution & precision in that case.

When do we see Overflow and Underflow . Why double is considerd that unsupported in fixed point converter?

I think log (Natural logarithm) is unsupported. We need common logarithm base 10.

How enable logging Mode fipref ? How it help me in verification

Can you please help?Thank you!

Life is Wonderful 2020-11-21

编辑：Life is Wonderful 2020-11-21

在 MATLAB Online 中打开

I found the right implementation -

    qsb  = fixed.Quantizer(numerictype(1,32,24));
    y0  = quantize(qsb,20*fi(log(double(x)),1,32,24)/fi(log(double(10)),1,32,24)); % log(x)/log(10) for log base 10 i.e. log10
    y1 = 20*log10(x);

Question - Matlab fixed point suggestion using fi(value) is not reliable .I don't know why it suggest that results in overflow.

You can try fi(3)

WL =16

FL= 13

Signedness =1

Try , you can see overflow. For me its not clear . Please help me

Thanks

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Fixed point coder log10 implementation

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