[Top][All Lists]

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
## Re: [Help-gsl] Getting the index of a sorted vector entry closest to a c

**From**: |
Brian Gough |

**Subject**: |
Re: [Help-gsl] Getting the index of a sorted vector entry closest to a certain value |

**Date**: |
Fri, 11 Jun 2010 21:49:41 +0100 |

**User-agent**: |
Wanderlust/2.15.6 (Almost Unreal) Emacs/23.2 Mule/6.0 (HANACHIRUSATO) |

At Tue, 8 Jun 2010 13:31:29 -0700,
Luke wrote:
>* *
>* I have a gsl_vector whose values are evenly space from -M_PI to M_PI.*
>* I am using the GSL single dimensional root finding algorithm on a*
>* single equation which gives me a value that is in the range of [-M_PI,*
>* M_PI], but won't be exactly equal to any of the elements. My goal is*
>* to find the index of the element in my gsl_vector which is closest to*
>* the solution from the root finding algorithm. Here is an illustration*
>* of situation:*
>* *
>* v = {-1.0, -0.5, 0.0, 0.5, 1.0}*
>* x_star = 0.3*
>* *
>* Since the entry of v closest to x_star is 0.5, the index I would want*
>* to obtain is i = 3.*
>* *
>* I would imagine the function call to be something like:*
>* *
>* i = get_nearest_index(v, x_star);*
Hi
See the Interpolation chapter of the manual in the section on "Index
Look-up and Acceleration"
--
Brian Gough