Re: [ccp4bb] R: [ccp4bb] AW: [ccp4bb] uncertainites associated with intensities from twinned crystals; Sorry for HTML.

2013-11-07 Thread Tim Gruene
-BEGIN PGP SIGNED MESSAGE- Hash: SHA1 Dear Jens, thanks for setting this right. Best, Tim On 11/07/2013 07:53 AM, Jens Kaiser wrote: > Fulvio, Tim, error propagation is correct, but wrongly applied in > Tim's example. s_f= \sqrt{ \left(\frac{\partial f}{\partial {x} > }\right)^2 s_x^2 +

Re: [ccp4bb] R: [ccp4bb] AW: [ccp4bb] uncertainites associated with intensities from twinned crystals; Sorry for HTML.

2013-11-06 Thread Jens Kaiser
Fulvio, Tim, error propagation is correct, but wrongly applied in Tim's example. s_f= \sqrt{ \left(\frac{\partial f}{\partial {x} }\right)^2 s_x^2 + \left(\frac{\partial f}{\partial {y} }\right)^2 s_y^2 + \left(\frac{\partial f}{\partial {z} }\right)^2 s_z^2 + ...} (see http://en.wikipedia.org/wi

Re: [ccp4bb] R: [ccp4bb] AW: [ccp4bb] uncertainites associated with intensities from twinned crystals

2013-11-06 Thread Tim Gruene
-BEGIN PGP SIGNED MESSAGE- Hash: SHA1 Dear Fulvio, with simple error propagation, the error would be sigma(I(h1)) = (1-α)sigma(Iobs(h1))-α*sigma(Iobs(h2))/(1-2α) would it not? Although especially for theoretical aspects you should be concerned about division by zero. Best, Tim On 11/0

[ccp4bb] R: [ccp4bb] AW: [ccp4bb] uncertainites associated with intensities from twinned crystals

2013-11-06 Thread Fulvio Saccoccia
Thank you for reply. My question mostly concern a theoretical aspect rather than practical one. To be not misunderstood, what is the mathematical model that one should apply to be able to deal with twinned intensities with their errors? I mean, I+_what? I ask this In order to state some general