Enumerate the list of terms contained in a quadratic expression.

The value to be used as prev for the next call o NULL when all terms have been returned.

The following displays the terms of a quadratic expression:

void dispqexp(XPRMcontext ctx, mmquad_qexp q)
{
 void *prev;
 XPRMmpvar v1,v2;
 double coeff;
 int nlin,ct;
	
 mq->getqexpstat(ctx, quadctx, q, &nlin, NULL, NULL, NULL);
 ct=0;
 prev=mq->getqexpnextterm(ctx, quadctx, q, NULL, &v1, &v2, &coeff);
 mm->printf(ctx, "%g ", coeff);
 while(prev!=NULL) {
  prev=mq->getqexpnextterm(ctx, quadctx, q, prev, &v1, &v2, &coeff);
  if(ct<nlin) { mm->printf(ctx,"%+g %p", coeff, v2); ct++; }
  else mm->printf(ctx,"%+g %p * %p", coeff, v1, v2);
 }
 mm->printf(ctx,"\n");
} 

This function can be called repeatedly to enumerate all terms of a quadratic expression. For the first call, the parameter prev must be NULL and the function returns the constant term of the quadratic expression (for v1 and v2 the value NULL is returned and coeff contains the constant term). For the following calls, the value of prev must be the last value returned by the function. The enumeration is completed when the function returns NULL.
If this function is called repeatedly, after the constant term it returns next all linear terms and then the quadratic terms.

mmquad