Spearman’s Rho test

The code performs Spearman's rho test. It tests the null hypothesis of trend absence in the vector V, against the alternative of trend.
The result of the test is returned in Td = 1 indicates positive trend Td = -1 indicates negative trends, i.e., a rejection of the null hypothesis at the alpha significance level. Td = 0 indicates a failure to reject the null hypothesis at the alpha significance level.