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## Re: S: Example

**From**: |
Ted Harding |

**Subject**: |
Re: S: Example |

**Date**: |
Tue, 18 Jul 1995 19:01:38 +0200 (BST) |

( Re Message From: Nils Naumann )
>* sorry, if this is a to stupid question. But I have red the manual and*
>* played around a long time and I can't find a solution, except two for*
>* loops, which will be really slow. *
>* *
>* Doe's anyone have an example for changing elements of a matrix which*
>* match a special condition? I will change all members of a matrix which are *
>* lower than the value x to the value y.*
>* *
>* The manual wrote I should use a matrix returned by the comparison operator, *
>* but*
>* I can't figured out how I should pass this matrix to my expression.*
Hi Nils,
Let X be the matrix to change, and c a comparison constant.
Let U be a matrix such that you want to change
X(i,j) to U(i,j) if X(i,j) < c, otherwise X(i,j) is unchanged.
C = (X < c);
Y = (1-C).*X + C.*U;
You can also do
Y(C) = U(C);
provided you have set do_fortran_indexing="true", but the first method
always works (or should).
If you have trouble with this, get back to me.
best wishes,
Ted. (address@hidden)

**S: Example**, *Nils Naumann*, `1995/07/18`
**Re: S: Example**,
*Ted Harding* **<=**