# Modern Computational Finance book

#### ExSan

##### Active Member
is this a 1st edition???

Yes

#### Daniel Duffy

##### C++ author, trainer
I downloaded, inspected and ran the github code. I have a number of initial questions to make sure I am on the same wavelength. In particular, I never use adjectives in my work because they are subjective and context-sensitive:

1. What is the 'final' software product?
2. What is 'Modern C++'? (BTW that C++17 'constexpr' is incongruous and it's the shakiest syntax in C++11). The code I see is C++03 with a strong bias to C. To be honest, it has a 90s feel for me (disclaimer: I began C++ in 1987 and have seen many students along the way). In fairness, maybe the github code is not indicative.
3. Can you make 'professional implementation' more precise? You probably mean quality.
4. What's the rationale for C code Microsoft XLL Kit in the github offering?
Good definitions are important. I am not sure how to respond if these are not agreed on by all.

It is also good that discussion flow in two directions. I do have a number of suggestions to possibly help as new improvements going forward if you wish. A shameless self-promotion of my own is my (recent) 2nd edition Wiley book for computational finance in which C++11 syntax etc. is done in excruciating detail.

Quantnet and Baruch offer C++ and Advanced C++11 and C++14 courses and many members here will welcome advances in computational finance and certainly C++. Without being too bombastic about it, it is a kind of gold standard. There is a wonderful and knowledgeable C++ community here.

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#### antoinesavine

##### New Member

What is the 'final' software product?

This is not a software, but the companion code for my book Modern Computational Finance book with Wiley.

It looks like both of us published books with Wiley around the same time with similar titles but, I think, different contents. The principal focus of my book is adjoint differentiation (AD) and its automatic implementation (AAD). The book also teaches generic Monte-Carlo simulations (meaning modular in terms of models and products) with a strong focus on a parallel (multi-threaded) implementation, and instrumentation with AAD. My book teaches the implementation of all of these in C++, but it is not a book to learn C++, modern or otherwise. It is a book on AAD and Monte-Carlo, with implementation in C++.

This being said, the files AAD.h (with dependencies on gaussians.h and blocklist.h) form a self contained AAD framework, applicable not only for financial simulations but also FDM and other numerical implementations, as well calibration, back-propagation in deep learning and whatever application where many differentials of scalar results must be computed quickly. The files MC.h (with dependencies) constitute the skeleton of a generic (modular) Monte-Carlo framework, which can accommodate a wide range of models and products.

What is 'Modern C++'?

You are right, I should really specify what I mean since this word is thrown around a lot. What I mean is that the implementation strongly relies on some patterns, constructs and libraries from C++11 (threading, lambdas, move semantics...) and (much less) from C++ 14/17 like constexpr (which I happen to like a lot, I would be very happy to discuss C++ constructs with you privately, at your convenience).

What I don't do is systematically apply recent or fashionable design patterns. The focus is on code that runs fast (a critical requirement with the massive regulatory calculations demanded of banks) and may be easily reused, extended and modified (another key requirement in a fast changing environment). Under these constraints, I tried to make the code as easy to understand as possible by most quants, risk managers, developers, derivatives professionals and students, and so avoid elegant but complicated code unless necessary.

Finally, the design of the Monte-Carlo library is object oriented, which is maybe why it has this nostalgic 90s feel. I believe that OOD is still well suited to Monte-Carlo libraries, and I explain exactly why in the book.

Can you make 'professional implementation' more precise?

The wording 'professional implementation' is not a judgement about quality. What I mean is that the code in the book is implemented similarly to how we do it in banks, as opposed to a demonstration code just for the purpose of illustrating the concepts in the book.

For example, the code of my introductory presentation to AAD in machine learning and finance is not professional. This is demonstration code, simplified to the extreme, and biased towards C so it is understandable by anyone with minimum programming experience. The code for the presentation is gathered in a file named toyCode.h.

On the contrary, the code in the book is professional in the sense that it reflects the production code implemented in financial institutions (in banks anyway, I never worked for a fund but I do have 23 years experience in French, American, Japanese and Danish banks).

Why the Microsoft XLL kit?

This kit is necessary to export C++ code to Excel. For convenience, the code is exported to Excel so readers can easily and immediately replicate the results of the book or make calculations of their own.

In addition, I am often asked how to connect C++ with Excel. I ended up writing a tutorial here, which I made part of the GitHub repo because I did not want to include it in the book, where it would feel out of place. The tutorial is based on Microsoft's kit, it is meant for an audience who wants to quickly learn a recipe to export code to Excel and doesn't need to depth or detail of a complete reference like the (excellent) Dalton, also with Wiley.

Finally, my book is also the curriculum for my Computational Finance classes at Copenhagen University, where students are asked to produce XLLs for their hand-ins (again, because this is very convenient and because this is how it works in banks).

I do hope I clarified your concerns and I am happy to discuss more at your convenience, preferably on the phone or over coffee. I have every intention to read your book, and I would be honored if you read and reviewed mine, again, keeping in mind that my book does not teach C++, but the 'modern' algorithms and techniques recently introduced to finance, together with a professional implementation (now these terms are clarified) .

Congratulations and thank you for the good job training professional C++ coders for the financial industry.

Kind regards,

Antoine Savine

#### Daniel Duffy

##### C++ author, trainer
That's clear now, thanks, Antoine, also the term 'professional' which could be called 'production' I suppose. That's fine. This encompasses the constraints and use cases in software projects. I appreciate that real life demands being fast.. One aspect is that software is also a product which costs money to maintain but this is probably outside the scope here. Some products have long lifetimes (5-30 years). This has an influence on how one perceives software. (in life we strive 'get it working, then get it right, then and only then get it optimised' )

I like the template code for AD and Expressions (the latter being similar in spirit to stuff in my Boost I book). Maybe it could be used by students here for the Baruch advanced C++ where we have a defined architecture for applications (e.g. Monte Carlo). What would be nice is a plug-in AD component to compute the greeks? A narrow interface using C++11 std::function is good IMO.

Personally I am very interested in the maths in your book and then the (pseudo-code) algorithms that can be mapped to C++11.

I think it would be a good idea to use your book as foundation for students to learn more about AD (and ML, whatever that is). BTW, I am doing some work on the Complex Step Method (which is a well-kept secret but is used in practice).

Section 2.4 there discusses the connection with AD.

Some random thoughts:

1. Writing thread-safe, scalable(!) and speedy-up multi-threaded code is very difficult and I tend to avoid it myself (I don't work in real-time systems). Second, threads are applicable to asynchronous events and timing constraints and less so for compute-intense parallel processing. In that case tasking is better and more scalable and coarse-grained. IMO this is the model going forward (see libraries PPL and TBB). I really like those libraries.
2. I use Boost and open-source libraries in as far as possible. A bit like Fortran mindset. I suppose I am a Lego programmer!
3. C++17 has a lot of large-grained concurrency features coming down the track AFAIR.
4. I used XLL long time ago (not my cup of tea to be honest). These days Excel-DNA is extremely popular (C#,F#) but also C++/CLI which speaks native C++ and NET>
5. Smart pointers rulez?
A bit of a mouthful for a Sunday morning. I hope something was useful.

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#### antoinesavine

##### New Member
Thank you Daniel. I will be looking forward to working with you on incorporating AAD material. Kind regards.
Antoine

#### Daniel Duffy

##### C++ author, trainer
You're welcome, Antoine. Just a small remark. Call by reference of vectors might help performance. Saves memory thrashing?

C++:
void toyDupireBarrierMcRisks(
const double S0, const vector<double> spots, const vector<double> times, const matrix<double> vols,
const double maturity, const double strike, const double barrier,
const int Np, const int Nt, const double epsilon, RNG& random,

#### antoinesavine

##### New Member
Of course! Thank you Daniel.
This is part of the toy code, where I don’t worry about performance. In the ‘professional’ code I should never pass collections by value (unless I may still have mistakes left...)
This being said, the inputs are marked const so the compiler should catch and optimise easily.
Kind regards.
Antoine