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Partial trig functions

Does any programming language (including those embedded in statistical analysis packages) let you specify the domain of trig functions, or restrict them by default to a single cycle (eg 0-360 degrees)? I was reading this (please ignore the politics and point-scoring involved unless you enjoy that kind of thing) and wondered how common such errors were - I've certainly done similarly stupid things.

Another (better, since it would catch radians used as degrees, as well as being more general) solution would be physical units within the type system (although angles are dimensionless, so you'd need quite a pedantic system, I would guess).

((Unit) Tests pick up problems like this, of course).

By andrew cooke at 2004-08-26 17:22 | LtU Forum | previous forum topic | next forum topic | other blogs | 6333 reads

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Yes, Mathematica

Define functions with specified domains or solve equations with domain assumptions for the unknowns.

Other packages offer similar capabilities, but none as comprehensive to my knowledge.

By Mark Evans at Fri, 2004-08-27 02:29 | login or register to post comments

thanks! (some of that page is

thanks! (some of that page is a bit worrying - it's kind of teaching people maths by talking to a computer, and the reason cos(x) = sin(x+pi/2) seems to be because it looks right and mathematica says so. eek. but it's pretty impressive anyway.)

By andrew cooke at Fri, 2004-08-27 15:28 | login or register to post comments

Better math than the textbooks

Pedagogy assertions aside, mathematica says so can be more trustworthy than standard published reference works, with good reason.

Portal site.

By Mark Evans at Sat, 2004-08-28 05:41 | login or register to post comments