Articles by a modeler's tribulations, gopi goteti's web log

R code to obtain and plot rainfall data for the whole world

May 19, 2013 | 0 Comments

If you want to create rainfall maps for the whole world in R there is no readily available code or package to do this. Moreover, data publicly available from research institutions is not generally in plain text format or other familiar formats. Hydrological and climatological studies sometimes require rainfall data ... [Read more...]

Fixing non positive definite correlation matrices using R

October 14, 2012 | 0 Comments

Problem When a correlation or covariance matrix is not positive definite (i.e., in instances when some or all eigenvalues are negative), a cholesky decomposition cannot be performed. Sometimes, these eigenvalues are very small negative numbers and occur due to rounding or due to noise in the data. In simulation ... [Read more...]

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