Secant Method

Secant Method - Calculation time increases non-linearly with number of iterations - Messages

#1 Posted: 12/14/2014 11:33:51 AM
Brian Runagle

Brian Runagle

13 likes in 27 posts.

Group: User

Hi

I want to solve a complex non-linear equation using the Secant Method and decided to verify the algorithm with a simple function. For this test, I set the number of iterations to n, rather than check against an error threshold.

SMath gives the correct solution.

However, because the number of iterations is set by n, I would expect the calculation time to be proportional to n, but it increases very quickly as you can see from the attached file. So:

• have I done something silly in the algorithm?
• is there something different I need to do when using SMath?
• any other ideas?

Many thanks

Brian
Secant Method - Test.sm (6 KiB) downloaded 65 time(s).
#2 Posted: 12/14/2014 12:04:35 PM
Davide Carpi

Davide Carpi

1415 likes in 2872 posts.

Group: Moderator

Hi bdrunagle,

This happens because each result doesn't contains a number, but the whole set of numbers involved up to that iteration.
Use an eval at each iteration to store just the result and speed up the calculation.
2014-12-14 16_03_08-SMath Studio Desktop - [Secant Method - Test.sm_].png
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#3 Posted: 12/14/2014 5:00:08 PM
Brian Runagle

Brian Runagle

13 likes in 27 posts.

Group: User

That's just what I needed!

Thanks very much Davide.
#4 Posted: 12/15/2014 4:06:45 AM
Davide Carpi

Davide Carpi

1415 likes in 2872 posts.

Group: Moderator

You are welcome

Best regards,

Davide
If you like my plugins please consider to support the program buying a license; for personal contributions to me: paypal.me/dcprojects
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