/* PROCEDURE covsrt
/* Marquart-Levenworth Covariance Determination adapted to PL/SQL. */

CREATE OR REPLACE PROCEDURE covsrt(pCovar IN OUT IC50_ENGINE.MultiDNumTabType,
                                   pMa IN NUMBER,
                                   pIa IN IC50_ENGINE.NumTabType,
                                   pMfit IN NUMBER)
AS
/* pCovar is the input covariance matrix, which will be expanded and output.
   pMa is the total number of parameters, = 4 for IC50.
   pIa is the status of each of the 4 parameters, 0 = fixed and 1 = variable.
   pMfit is the number of variable parameters, from 1 to 4.
   expand the covariance matrix to use the fixed parameters,
   not just the variable parameters.
   fixed parameters have 0 covariance. */
i NUMBER;
j NUMBER;
k NUMBER;
/* swap - only used in SWAP in book. */

BEGIN

  FOR i IN pMfit+1..pMa LOOP
    FOR j in 1..i LOOP
/* pCovar(i,j) = 0 */
      pCovar((i - 1) * 4 + j) := 0.0;
/* pCovar(j,i) = 0 */
      pCovar((j - 1) * 4 + i) := 0.0;
    END LOOP;
  END LOOP;
  
  k := pMfit;

  FOR j IN REVERSE 1..pMa LOOP
    IF pIa(j) <> 0 THEN
      FOR i IN 1..pMa LOOP 
/* pCovar(i,k) for pCovar(i,j) */
        SWAP(pCovar((i - 1) * 4 + k), pCovar((i - 1) * 4 + j));
      END LOOP;
      FOR i IN 1..pMa LOOP
/* pCovar(k,i) for pCovar(j,i) */
        SWAP(pCovar((k - 1) * 4 + i), pCovar((j - 1) * 4 + i));
      END LOOP;
      k := k - 1;
    END IF;
  END LOOP;

END;
/
SHOW ERRORS PROCEDURE covsrt;