share/contrib/wrstcse.dem

   1 load("wrstcse")$ratprint:false$
   2 load("engineering-format")$
   3 engineering_format_min: .01$engineering_format_max: 1100$fpprintprec: 6$
   4
   5 printf(false,"The output voltage of a voltage divider");
   6 div1:I=U_In/(R_1+R_2);
   7 div2:U_Out=I*R_2;
   8 div:subst(div1,div2);
   9
  10 printf(false,"Every store keeps 1% resistors or better.");
  11
  12 vals_discrete:[
  13     R_1=10e3*(1+.01*tol[1]),
  14     R_2=1e3* (1+.01*tol[2])
  15 ];
  16 wc_inputvalueranges(vals_discrete);
  17
  18 assume(U_In>0);
  19 wc_typicalvalues(subst(vals_discrete,div));
  20 lhs(div)=wc_mintypmax(subst(vals_discrete,rhs(div)));
  21 printf(false,"Trying more values per resistor to verify this result:");
  22 lhs(div)=wc_mintypmax(subst(vals_discrete,rhs(div)),40);
  23 printf(false,"Trying 100 random values per resistor to verify this result:");
  24 lhs(div)=wc_mintypmax(subst(vals_discrete,rhs(div)),-100);
  25
  26 printf(false,"Inside a semiconductor tolerances are big but tightly coupled:");
  27 vals_ic:[
  28     R_1=10e3*(1+.2*tol[1]+.0001*tol[2]),
  29     R_2=1e3* (1+.2*tol[1]+.0001*tol[3])
  30 ];
  31 wc_inputvalueranges(vals_ic);
  32 lhs(div)=wc_mintypmax(subst(vals_ic,rhs(div)));
  33
  34 printf(false,"An asymmetric tolerance range:");
  35
  36 vals_t:[
  37     R_1=10e3*(1+.01*tol[1]),
  38     U_BE=wc_mintypmax2tol(tol[2],.6,.75,.85)
  39 ];
  40 wc_inputvalueranges(%);
  41 ib:I_B=(U_In-U_BE)/R_1;
  42
  43 lhs(ib)=wc_mintypmax(subst(vals_t,rhs(ib)));
  44 printf(false,"This result is correct. An additional assumption makes it simpler:");
  45 assume(U_In>10);
  46 lhs(ib)=wc_mintypmax(subst(vals_t,rhs(ib)));
  47 wc_systematic(subst(vals_t,rhs(ib)));
  48 apply('min,%);