Log10 Matlab
Charise Scrivner
Y = log10(X) returnsthe common logarithm of each element in array X.The function accepts both real and complex inputs. For real valuesof X in the interval (0, Inf), log10 returnsreal values in the interval (-Inf ,Inf).For complex and negative real values of X, the log10 functionreturns complex values.
If the output of the function running on the GPU can be complex, then you must explicitly specify its input arguments as complex. For more information, see Work with Complex Numbers on a GPU (Parallel Computing Toolbox).
The log10 function can calculate on all variables within a table or timetable without indexing to access those variables. All variables must have data types that support the calculation. For more information, see Direct Calculations on Tables and Timetables.
The error message tells you what the problem is, you've tried to apply the log10 function to a value of type uint8 and the function is not defined for that type of number. What you haven't realised is that imread, when an image file meets certain criteria (read the documentation for what those criteria are) will capture the pixel data into an array of uint8s, not real numbers.
If you want to take the logarithm of a uint8 you'll either have to define a logarithm function of your own which takes such inputs, or, more straightforward, cast the uint8 to a type which log10 is happy with. For example, you could write:
And by now you'll have realised why your diagnostic test didn't tell you anything useful, when you execute the command log10(190) Matlab, by default, decides that 190 is of type double and computes the logarithm without complaint. log10(uint8(190)) tells a different story.
Originally, computed PSD is in power^2/hz. Then I go to matlab command, and run Data = log(Data.*10^12). Is it right formula? All values I get are negative. Is the outcome data divided by Hz as in the formula above (log(power^2/hz))?
Z-score with respect to what?
The Z-score normalization available in the process "Baseline normalization" estimates the mean and variance computed over a baseline time segment. Your PSD doesn't have any time dimension.
Hi Niko. That doesn't sound very meaningful to me. The mean power (and std) varies a lot across frequency. So you'd get a spectrum that would look the same, but scaled into this "Z-scores" that cannot be interpreted as usual, e.g. for a statistical threshold.
Cheers
That seems like a valid Z-score transformation to me, if that's what you're interested in: how individuals' power values compare with the population distribution. In practice though you don't have the population standard dev (only your sample's), so I believe it's actually a t-statistic.
Does someone know what the difference is between the log and log10 transformation in JMP? I cannot find any information on it... I discovered that they do not give the same result and I wonder what the reason is.
Th ability to write custom functions within Matlab lends an extrodinary amount of power to the user. In this example, we will write a function that will compute the friction factor as a function of the Reynolds number and the relative roughness: epsilon / diameter.
To begin, all functions within matlab must begin by declaring that m-file is a function. This is accomplished by having the first line of the m-file having the word 'function' followed by the name of the variable which will be returned. This is consequently set equal to the name of the name of the file with the quantities that are passed to the function in parenthesis. For the purpose of this excersize, the name of the function will be 'moody' and the first line of the function is as follows:
The next step is to use a series of conditional tests to determine if the Reynolds number is in an appropriate range for the application of the moody chart. The first conditional statement tests to see if the Reynolds number is positive and if not displays a warning. The 'error' command will cause the script to quit without finishing if the condition proves to be true.
The 'return' command causes the script to terminate and since the value of 'f' is assigned, this is the value returned by the function. The conditional statments are terminated by the use use of the 'emd' command.
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The COVID-19 outbreak led to the discovery of SARS-CoV-2 in sewage; thus, wastewater treatment plants (WWTPs) could have the virus in their effluent. However, whether SARS-CoV-2 is eradicated by sewage treatment is virtually unknown. Specifically, the objectives of this study include (i) determining whether a mixed matrixed membrane (MMM) is able to remove SARS-CoV-2 (polycarbonate (PC)-hydrous manganese oxide (HMO) and PC-silver nanoparticles (Ag-NP)), (ii) comparing filtration performance among different secondary treatment processes, and (iii) evaluating whether artificial neural networks (ANNs) can be employed as performance indicators to reduce SARS-CoV-2 in the treatment of sewage. At Shariati Hospital in Mashhad, Iran, secondary treatment effluent during the outbreak of COVID-19 was collected from a WWTP. There were two PC-Ag-NP and PC-HMO processes at the WWTP targeted. RT-qPCR was employed to detect the presence of SARS-CoV-2 in sewage fractions. For the purposes of determining SARS-CoV-2 prevalence rates in the treated effluent, 10 L of effluent specimens were collected in middle-risk and low-risk treatment MMMs. For PC-HMO, the log reduction value (LRV) for SARS-CoV-2 was 1.3-1 log10 for moderate risk and 0.96-1 log10 for low risk, whereas for PC-Ag-NP, the LRV was 0.99-1.3 log10 for moderate risk and 0.94-0.98 log10 for low risk. MMMs demonstrated the most robust absorption performance during the sampling period, with the least significant LRV recorded in PC-Ag-NP and PC-HMO at 0.94 log10 and 0.96 log10, respectively.
En MATLAB, la fonction logarithme nprien ou naturel, que l'on note souvent ln en mathmatiques, s'appelle log . Tandis que le logarithme commun, en base 10, que l'on note souvent log s'appelle log10.
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