/******  Significant Digits ***********************
Author: Cameron Rookley
        http://www.goodnet.com/~dh74673/home.htm
Date:   20 July 1999

This code is provided gratis, without performance
warrantee, for private non-commercial use.

Here is a proc (scroll down) with some test code to
round a vector x to d significant digits, where d is
conformable with x.

syntax: newvalues=siground(oldvalues,numsigdigs);
****************************************************/

/* test code */
new;
cls;
x=1511.36|313.245|(-42.324)|(-0.2254)|(-0.00032546);
d=3|2|4|2|5;
newx=siground(x,d);
print x~newx;
stop;

proc(1)=siground(x,d);
local scfactor,newx;
/* first get scale factor */
scfactor=floor(ln(abs(x))./ln(10));
newx=(x.*(10.^(-scfactor)));
newx=round(newx.*(10.^(d-1)))./(10.^(d-1));
newx=newx.*(10.^scfactor);
retp(newx);
endp;