A new routine PDA_SUMSL has been added which performs unconstrained minimisation allowing gradients to be supplied in addition to function values.

- The use of the higher level ERR and MSG error reporting libraries within PDA has been replaced by use of the lower level EMS library (see section 7).
- The following areas have had new routines added:
- Matrices.
- Minimisation.
- Normal distribution.
- Pseudo-random numbers.
- Simple statistics.
- Sorting.
- Two-dimensional interpolation and fitting.

The new routines are:

- PDA_BISPEV
- - Evaluates the bivariate spline approximation found by PDA_SURFIT.
- PDA_CHE2D
- - Evaluates a 2-dimensional Chebyshev polynomial
- PDA_COVMAT
- - Approximates the covariance matrix of normal order statistics.
- PDA_DB2INK
- - Deterimines a piecewise polynomial function that interpolates 2-D gridded data.
- PDA_DB2VAL
- - Evaluates the function found by PDA_DB2INK.
- PDA_DCOV
- - Calculates the covariance matrix for a nonlinear data fitting problem.
- PDA_DNLS1
- - Minimises the sum of squares of M non-linear functions.
- PDA_DNLS1E
- - Minimises the sum of squares of M non-linear functions (easy version).
- PDA_DQED
- - Solves bounded nonlinear least squares and nonlinear equations.
- PDA_IDBVIP
- - Performs 2-D bivariate interpolation on irregularly scattered data.
- PDA_IDSFFT
- - Performs smooth surface fitting on irregular data.
- PDA_IPERM
- - Forms the inverse of a permutation.
- PDA_LSQR
- - Solves sparse unsymmetric linear, and damped, least squares problems.
- PDA_NSCOR
- - Calculates the approximate expected values of normal order statistics.
- PDA_PPND16
- - Returns the normal deviate corresponding to a given lower tail area of P.
- PDA_QSAx
- - Sort an array into ascending order.
- PDA_QSDx
- - Sort an array into descending order.
- PDA_QSIAx
- - Sort an array of pointers to access an array in ascending order.
- PDA_QSIDx
- - Sort an array of pointers to access an array in descending order.
- PDA_RAND
- - Returns pseudo-random numbers in the range 0 to 1.
- PDA_RNEXP
- - Returns pseudo-random numbers from an exponential distribution.
- PDA_RNGAM
- - Returns pseudo-random numbers from a gamma distribution.
- PDA_RNNOR
- - Returns pseudo-random numbers from a Gaussian distribution.
- PDA_RNPOI
- - Returns pseudo-random numbers from a Poisson distribution.
- PDA_RNSED
- - Sets the seed for the PDA random-number generators.
- PDA_RINP
- - Reorders an array in place using a permutation index.
- PDA_SAAC
- - Sorts the columns of a two dimensional array into ascending order.
- PDA_SAAR
- - Sorts the rows of a two dimensional array into ascending order.
- PDA_SURFIT
- - Find a bivariate spline approximation to irregularly spaced 2-D data.
- PDA_V11
- - Calculates an approximation to the variance of the largest normal order statistic.