# Alpha\_multiplier **URL:** \ **Category:** Support\ **Created:** [December 3, 2013, 4:10pm UTC](https://mworks.discourse.group/t/alpha-multiplier/601 "2013-12-03T16:10:25Z")\ **Posts on this page:** 6\ **Page:** 1
**Author:** ![cstawarz](https://yyz1.discourse-cdn.com/flex031/user_avatar/mworks.discourse.group/cstawarz/32/3_2.png) [@cstawarz](https://mworks.discourse.group/u/cstawarz)\ **Post date:** [December 3, 2013, 4:10pm UTC](https://mworks.discourse.group/t/alpha-multiplier/601/1 "2013-12-03T16:10:25Z")
Hi! I’m a phd student at the German primate centre (DPZ). I need your help please! I encountered a problem while reading the .mwk file. When the data is imported to matlab, the feature field “alpha\_multiplier” of the two stimuli: “fixation point stimulus” & the “ellipse stimulus” does not exist, as if the .mwk file does not hold that information. However it does exist for say the “dynamic random dots” stimulus. Could this reflect a problem with the core code of the program? I’m using: Version 0.5 (73eb095) I would really appreciate to know what you think. All the best, Amr Maamoun ---
**Author:** ![cstawarz](https://yyz1.discourse-cdn.com/flex031/user_avatar/mworks.discourse.group/cstawarz/32/3_2.png) [@cstawarz](https://mworks.discourse.group/u/cstawarz)\ **Post date:** [December 3, 2013, 8:16pm UTC](https://mworks.discourse.group/t/alpha-multiplier/601/2 "2013-12-03T20:16:53Z")
Hi Amr, I’ve confirmed that this is a problem in the implementation of these stimuli. The fixation point, ellipse, image file, and rectangle stimulus types all support the “alpha\_multiplier” parameter but fail to log its value to the event stream. This appears to be a long-standing issue. Thank you for bringing it to our attention! This will be an easy fix on my end. Unfortunately, it won’t help for any existing data files, since the values simply aren’t there. However, you should still be able to determine the alpha\_multiplier value for any stimulus presentation, since for a given stimulus, the alpha\_multiplier parameter is either a constant (meaning the value can be read from the experiment file) or a variable (meaning the alpha\_multiplier value will be equal to the value of the variable _at the time the stimulus was enqueued_). If you need assistance in doing this, I’d be happy to help. Cheers, Chris Stawarz ---
**Author:** ![cstawarz](https://yyz1.discourse-cdn.com/flex031/user_avatar/mworks.discourse.group/cstawarz/32/3_2.png) [@cstawarz](https://mworks.discourse.group/u/cstawarz)\ **Post date:** [December 4, 2013, 3:43pm UTC](https://mworks.discourse.group/t/alpha-multiplier/601/3 "2013-12-04T15:43:55Z")
Hi Chris, thank you for the quick reply. What should be the next step for me? wait until a new version is issued? Cheers, Amr ---
**Author:** ![cstawarz](https://yyz1.discourse-cdn.com/flex031/user_avatar/mworks.discourse.group/cstawarz/32/3_2.png) [@cstawarz](https://mworks.discourse.group/u/cstawarz)\ **Post date:** [December 4, 2013, 5:22pm UTC](https://mworks.discourse.group/t/alpha-multiplier/601/4 "2013-12-04T17:22:48Z")
Hi Amr, I can get the fix in to the MWorks nightly build very soon. However, the nightly also includes other post-0.5 changes. If you’re uncomfortable with that, then the other option is to wait for the next official release (which should go out in the next couple months). Chris ---
**Author:** ![cstawarz](https://yyz1.discourse-cdn.com/flex031/user_avatar/mworks.discourse.group/cstawarz/32/3_2.png) [@cstawarz](https://mworks.discourse.group/u/cstawarz)\ **Post date:** [December 4, 2013, 5:36pm UTC](https://mworks.discourse.group/t/alpha-multiplier/601/5 "2013-12-04T17:36:05Z")
Hi Chris, OK. I’ll work around the problem until the next version is out. Thank you again for your help! Amr ---
**Author:** ![cstawarz](https://yyz1.discourse-cdn.com/flex031/user_avatar/mworks.discourse.group/cstawarz/32/3_2.png) [@cstawarz](https://mworks.discourse.group/u/cstawarz)\ **Post date:** [July 19, 2022, 11:20pm UTC](https://mworks.discourse.group/t/alpha-multiplier/601/6 "2022-07-19T23:20:38Z")