Accuracy of integer operations

[Harlan Gilbert]

Bruce,

Whereas Python has virtually infinite accuracy for integer operations such as multiplication and powers, Glowscript is giving me only six digits of accuracy, going quickly into floating point numbers for largish (actually not even very large) numbers.

Having only six digits of accuracy is a real problem for number theory work (for example, an implemention of the Diffie-Hellman public key cipher).

There may be no full solution, but if Python at least used double precision values by default, it would improve things.

Thanks for considering,

Harlan

[Bruce Sherwood]

GlowScript DOES use double precision. But by default the print statement displays 6 figures. See the documentation on "print_options" at https://www.glowscript.org/docs/VPythonDocs/text_output.html to change the default. 

Bruce

[Harlan Gilbert]

Thanks!  This fixed it.

On Thu, Oct 22, 2020 at 6:39 PM Bruce Sherwood <bruce.s...@gmail.com> wrote:

GlowScript DOES use double precision. But by default the print statement displays 6 figures. See the documentation on "print_options" at https://www.glowscript.org/docs/VPythonDocs/text_output.html to change the default. 

Bruce

--

---
You received this message because you are subscribed to a topic in the Google Groups "Glowscript Users" group.
To unsubscribe from this topic, visit https://groups.google.com/d/topic/glowscript-users/PFXluzssirU/unsubscribe.
To unsubscribe from this group and all its topics, send an email to glowscript-use...@googlegroups.com.
To view this discussion on the web visit https://groups.google.com/d/msgid/glowscript-users/CA%2BWuaSdqUg-b1kmXkBcoZ2y%3DC62OpHQh1XHGhpBRA%3D60G0oPTw%40mail.gmail.com.

--

Harlan Gilbert

Co-Chair and Math, Physics, Computer Science, and Philosophy Teacher

Green Meadow Waldorf High School

Chestnut Ridge, NY 10977

(845) 356-2514 x. 114

[pri...@gmail.com]

For b=14 the snippet below prints 1.6384e+4 1.6384e+4. Can I get 16384 instead?

And is there no way to handle more than 15 digits?

Web VPython 3.2
print_options(digits=15)
a=2
b=14
x1=pow(a,b)
x2=a**b
print(x1,x2)

Poul Riis

[Bruce Sherwood]

Here is the documentation on how to format text output:

    https://www.glowscript.org/docs/VPythonDocs/text_output.html

15 digits is all that a "double" (64-bit) number can span.

Bruce