04 September 2021   4:13:18.919 PM

cauchy_principal_value_test():
  FORTRAN90 version
  Test cauchy_principal_value().

cauchy_principal_value_test01():
  cpv() computes cauchy principal value of
  Integral ( -1 <= t <= 1 ) exp(t) / t dt

   N           Estimate             Error

   2     2.112977728449278        0.152402E-02
   4     2.114501718105385        0.326446E-07
   6     2.114501750751336        0.133626E-11
   8     2.114501750751458        0.145750E-11

cauchy_principal_value_test02():
  cpv() computes cauchy_principal_value of
  Integral ( 1-delta <= t <= 1+delta ) 1/(1-t)^3 dt )
  Try this for delta = 1, 1/2, 1/4.

   N          Estimate                  Exact                  Error

   2 -0.7397260273972603       -0.7363873204868445        0.333871E-02
   4 -0.7364116807468272       -0.7363873204868445        0.243603E-04
   6 -0.7363867923558026       -0.7363873204868445        0.528131E-06
   8 -0.7363873252791506       -0.7363873204868445        0.479231E-08

   2 -0.3425852498017447       -0.3425632583544805        0.219914E-04
   4 -0.3425633493215302       -0.3425632583544805        0.909670E-07
   6 -0.3425632583024640       -0.3425632583544805        0.520165E-10
   8 -0.3425632583544880       -0.3425632583544805        0.754952E-14

   2 -0.1678240178701501       -0.1678238552950642        0.162575E-06
   4 -0.1678238554770549       -0.1678238552950642        0.181991E-09
   6 -0.1678238552950588       -0.1678238552950642        0.538458E-14
   8 -0.1678238552950641       -0.1678238552950642        0.138778E-15

cauchy_principal_value_test():
  Normal end of execution.

04 September 2021   4:13:18.919 PM