search for: trapezoidal

...function name from "integrate" to "bv.integrate". To integrate f(x,y)=sin(x + y) over the unit square, it works: > bv.integrate(function(x, y) sin(x + y), c(0,0), c(1,1)) [1] 0.773651 (compare with .7736445 calculated from 2sin(1)*(1 - cos(1))) Then I write a function using trapezoidal rule as follows: trapezoidal <- function(f, a, b, n=100) { h <- (b - a)/n i <- 1:n sum(f(a + (i - 1)*h), f(a + i*h))*h/2 } I checked with > trapezoidal(sin, 0, 1) [1] 0.4596939 > 1 - cos(1) [1] 0.4596977 and > trapezoidal(dnorm, -3, 3) [1] 0.9972922 > diff(pnorm(...

Dear R Users, I've never used R before and my professor has asked us to do some pretty intense programming (or it's intense to me at least). Here is the question: Modify the function myquadrature inside the script so that it returns the quadrature of descrete data using the trapezoidal rule. Modify the call to the function at the bottom of the script so that is uses your modifies routine to compute the total volume flux through a transect using descrete observations of bathymetry and vertically-averaged velocity. The professor supplied us with some sample code and i'm prett...

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...d(size(f)); nint = npts -1; %number of intervals if(npts <=1) error('need at least two points to integrate') end; % set the grid spacing if(b <=a) error('something wrong with the interval, b should be greater than a') else dx = b/real(nint); end; npts = prod(size(f)); % trapezoidal rule % can code in line, hint: sum of f is sum(f) % last value of f is f(end), first value is f(1) % code below int=0; for i=1:(nint) %F(i)=dx*((f(i)+f(i+1))/2); int=int+dx*((f(i)+f(i+1))/2); end %int=sum(F); Then to call "myquadrature" I did: % example function call test the u...

Hi all, I would like to calculate the area under the ROC curve for my predictive model. I have managed to plot points giving me the ROC curve. However, I do not know how to get the value of the area under. Does anybody know of a function that would give the result I want using an array of specificity and an array of sensitivity as input? Thanks, Olivier -- View this message in context:

Dear All,   as a follow up to my previous e-mail (I think I am getting closer...):   I am trying to apply the trapezoidal functions to a matric column by column. I have the following code:   a <-matrix(c(1:100),ncol=10) b <-matrix(c(2,4,6,8,10,12,14,16,18,20))   apply(a,2,function(b,a) sum(diff(b)*(a[-1]+a[-length(a)]))/2)   for some reason i get an error message: Error in FUN(newX[[, i], ...): argument "a&...

I have the following code for the minimum and maximum of my prediction interval > y.down=lines(x[x.order], set1.pred[,2][x.order], col=109) > y.up=lines(x[x.order], set1.pred[,3][x.order], col=109) domain=min(x):max(x) polygon(c(domain,rev(domain)),c(y.up,rev(y.down)),col=109) It doesnt seem to shade the right region, it gives me a trapezoid. Any help? Thanks!

Release 2.21.3 (2013-02-20) =========================== A few minor bugfixes, another point release. * Fix tracking of DRI pixmaps and their backing bo across reparenting. If we tried to execute a SwapBuffers after a Window was reparented, but before the DRI client has updated its references, then we would end up manipulating an exported pixmap without a flush flag set. In the worst

Dear All, I need to perform a numerical integration of one dimensional fucntions. The extrems of integration are both finite and the functions I'm working on are quite complicated. I have already tried both area() and integrate(), but they do not perform well: area() is very slow and integrate() does not converge. Are in R other functions for numerical integration of one dimentional

Hi there, I want to integrate a function over an irregular polygon. Is there any function which can implement this easily? Otherwise, I am thinking of divide the polygon into very small rectangles and use "adapt" to approximate it. Do you have any suggestions to get the fine division? Any advice is appreciated. Haiyong

...r Curve (AUC) for many parameter combinations. I am using the ROC library and the following commands to generate each AUC: rocobj=rocdemo.sca(truth = ymis, data = model$fitted.values, rule = dxrule.sca) #generation of observed ROC object aucobj=AUC(rocobj) #pulling out just the observed AUC - trapezoidal not integrated but they are pretty slow. Does anyone know of a faster way to get the AUC? Thanks, Nina [[alternative HTML version deleted]]

It is A Good Thing to regularize Authors and Maintainers of packages, particularly for citation() and toBibTex(). Could I add a suggested TODO item for the maintainer of package.skeleton and friends to help reinforce this for new packages: - Please add appropriate templates for Author at R in the skeleton DESCRIPTION file generated, indicating the proper format as well as the use of role= to

Hi, I would like to calculate the area under segmented regression lines (single breakpoints). I had thought that I could do this using the predict() function to ascertain some key x y values in order to determine the dimensions for two trapezoids (under each segment of my regression). However, I've not had any success with this and have just read online that the predict function does not work

https://bugs.freedesktop.org/show_bug.cgi?id=35630 Summary: NV31: PFIFO_DMA_PUSHER while running x11perf Product: xorg Version: git Platform: x86 (IA32) OS/Version: All Status: NEW Severity: normal Priority: medium Component: Driver/nouveau AssignedTo: nouveau at lists.freedesktop.org

I would like a 3d plot of a matrix such that individual trapezoids that make up the surface are colored according to the z-value of that point (or preferably the midpoint of its four corners, or something similar). MS Excel has something like that. I know that persp can have an nx by ny matrix its "col" argument, I just don't know how to generate that matrix. To calculate the

Dear R users, I have spectral data (say, wavelength vs. extinction coefficient) for which I??d like to calculate an integral (i.e. the area underneath the curve). Suppose the (artificial) dataset is lambda E 1 2 2 4 3 5 4 8 5 1 6 5 7 4 8 9 9 8 10 2 How can I calculate an integral for these values using R? Many thanks for any help! Regards Christoph

Dear R-experts: I am using a function called AUC whose arguments are data, time, id, and dv. data is the name of the dataframe, time is the independent variable column name, id is the subject id and dv is the dependent variable. The function computes area under the curve by trapezoidal rule, for each subject id. I would like to embed this in aggregate to further subset by each Cycle, DoseDayNominal and Drug, but I can't seem to get the aggregate syntax correct. All the examples I can find use single column function such as mean, whereas this AUC function requires four argu...

Release 2.21.0 (2013-02-01) =========================== A few new features: * Enable render acceleration for Haswell GT1/GT2. * Enable multi-threaded rasterisation of trapezoids and fallback composition * Utilile a new kernel interface (v3.9) for processing relocations along with a few older features from the 2.20.x series: * PRIME support for hotplug GPUs and hybrid systems * Support

Hi, I am new to R and I would like to display an image on a plane in a 3D plot, i.e. I would like to be able to specify a theta and a phi parameters like in the function persp to display a 2D image on an inclined plane. Regards, vincent [[alternative HTML version deleted]]

Hi, I am new to R and I would like to display an image on a plane in a 3D plot, i.e. I would like to be able to specify a theta and a phi parameters like in the function persp to display a 2D image on an inclined plane. Regards, vincent [[alternative HTML version deleted]]