19,471 research outputs found
SWATI: Synthesizing Wordlengths Automatically Using Testing and Induction
In this paper, we present an automated technique SWATI: Synthesizing
Wordlengths Automatically Using Testing and Induction, which uses a combination
of Nelder-Mead optimization based testing, and induction from examples to
automatically synthesize optimal fixedpoint implementation of numerical
routines. The design of numerical software is commonly done using
floating-point arithmetic in design-environments such as Matlab. However, these
designs are often implemented using fixed-point arithmetic for speed and
efficiency reasons especially in embedded systems. The fixed-point
implementation reduces implementation cost, provides better performance, and
reduces power consumption. The conversion from floating-point designs to
fixed-point code is subject to two opposing constraints: (i) the word-width of
fixed-point types must be minimized, and (ii) the outputs of the fixed-point
program must be accurate. In this paper, we propose a new solution to this
problem. Our technique takes the floating-point program, specified accuracy and
an implementation cost model and provides the fixed-point program with
specified accuracy and optimal implementation cost. We demonstrate the
effectiveness of our approach on a set of examples from the domain of automated
control, robotics and digital signal processing
HUDDL for description and archive of hydrographic binary data
Many of the attempts to introduce a universal hydrographic binary data format have failed or have been only partially successful. In essence, this is because such formats either have to simplify the data to such an extent that they only support the lowest common subset of all the formats covered, or they attempt to be a superset of all formats and quickly become cumbersome. Neither choice works well in practice. This paper presents a different approach: a standardized description of (past, present, and future) data formats using the Hydrographic Universal Data Description Language (HUDDL), a descriptive language implemented using the Extensible Markup Language (XML). That is, XML is used to provide a structural and physical description of a data format, rather than the content of a particular file. Done correctly, this opens the possibility of automatically generating both multi-language data parsers and documentation for format specification based on their HUDDL descriptions, as well as providing easy version control of them. This solution also provides a powerful approach for archiving a structural description of data along with the data, so that binary data will be easy to access in the future. Intending to provide a relatively low-effort solution to index the wide range of existing formats, we suggest the creation of a catalogue of format descriptions, each of them capturing the logical and physical specifications for a given data format (with its subsequent upgrades). A C/C++ parser code generator is used as an example prototype of one of the possible advantages of the adoption of such a hydrographic data format catalogue
Workshop on Verification and Theorem Proving for Continuous Systems (NetCA Workshop 2005)
Oxford, UK, 26 August 200
Application-Specific Number Representation
Reconfigurable devices, such as Field Programmable Gate Arrays (FPGAs), enable application-
specific number representations. Well-known number formats include fixed-point, floating-
point, logarithmic number system (LNS), and residue number system (RNS). Such different
number representations lead to different arithmetic designs and error behaviours, thus produc-
ing implementations with different performance, accuracy, and cost.
To investigate the design options in number representations, the first part of this thesis presents
a platform that enables automated exploration of the number representation design space. The
second part of the thesis shows case studies that optimise the designs for area, latency or
throughput from the perspective of number representations.
Automated design space exploration in the first part addresses the following two major issues:
² Automation requires arithmetic unit generation. This thesis provides optimised
arithmetic library generators for logarithmic and residue arithmetic units, which support
a wide range of bit widths and achieve significant improvement over previous designs.
² Generation of arithmetic units requires specifying the bit widths for each
variable. This thesis describes an automatic bit-width optimisation tool called R-Tool,
which combines dynamic and static analysis methods, and supports different number
systems (fixed-point, floating-point, and LNS numbers).
Putting it all together, the second part explores the effects of application-specific number
representation on practical benchmarks, such as radiative Monte Carlo simulation, and seismic
imaging computations. Experimental results show that customising the number representations
brings benefits to hardware implementations: by selecting a more appropriate number format,
we can reduce the area cost by up to 73.5% and improve the throughput by 14.2% to 34.1%; by
performing the bit-width optimisation, we can further reduce the area cost by 9.7% to 17.3%.
On the performance side, hardware implementations with customised number formats achieve
5 to potentially over 40 times speedup over software implementations
Chameleon: A Hybrid Secure Computation Framework for Machine Learning Applications
We present Chameleon, a novel hybrid (mixed-protocol) framework for secure
function evaluation (SFE) which enables two parties to jointly compute a
function without disclosing their private inputs. Chameleon combines the best
aspects of generic SFE protocols with the ones that are based upon additive
secret sharing. In particular, the framework performs linear operations in the
ring using additively secret shared values and nonlinear
operations using Yao's Garbled Circuits or the Goldreich-Micali-Wigderson
protocol. Chameleon departs from the common assumption of additive or linear
secret sharing models where three or more parties need to communicate in the
online phase: the framework allows two parties with private inputs to
communicate in the online phase under the assumption of a third node generating
correlated randomness in an offline phase. Almost all of the heavy
cryptographic operations are precomputed in an offline phase which
substantially reduces the communication overhead. Chameleon is both scalable
and significantly more efficient than the ABY framework (NDSS'15) it is based
on. Our framework supports signed fixed-point numbers. In particular,
Chameleon's vector dot product of signed fixed-point numbers improves the
efficiency of mining and classification of encrypted data for algorithms based
upon heavy matrix multiplications. Our evaluation of Chameleon on a 5 layer
convolutional deep neural network shows 133x and 4.2x faster executions than
Microsoft CryptoNets (ICML'16) and MiniONN (CCS'17), respectively
Using financial futures in trading and risk management
The authors explain the features of an array of futures contracts and their basic pricing relationships and describe a few applications to show how investors and risk managers can use these contracts. Futures - and derivatives generally - allow economic agents to fine-tune the structure of their assets and liabilities to suit their risk preferences and market expectations. Futures are not a financing or investment vehicle per se, but a tool for transferring price risks associated with fluctuations in asset values. Some may use them to spread risk, others to take on risk. Financial futures (along with options) are best viewed as building blocks. Futures have facilitated the modern trend of separating conventional financial products into their basic components. They allow not only the reduction of transformation of investment risk but also the understanding and measurement of risk. The market for derivatives has grown enormously over the past decade. The value of exchange-traded eurodollar derivatives (futures and options) is equal to roughly 13 times the value of the underlying market. The volume of trading in financial futures now dwarfs the volume in traditional agricultural contracts. As emerging markets develop, given their inherently risky nature, expect financial futures to play a prominent role in risk management.Payment Systems&Infrastructure,Economic Theory&Research,International Terrorism&Counterterrorism,Banks&Banking Reform,Securities Markets Policy&Regulation,Commodities,Banks&Banking Reform,International Terrorism&Counterterrorism,Non Bank Financial Institutions,Economic Theory&Research
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