### 91.2 Functions and Variables for wrstcse

Function: wc_typicalvalues (expression, [num])

  Returns what happens if all tolerances (that are represented by tol [n] that can vary from 0 to 1) happen to be 0.

  Example:

      (%i1) load("wrstcse")$

      (%i2) vals: [
         R_1= 1000.0*(1+tol[1]*.01),
         R_2= 2000.0*(1+tol[2]*.01)
       ];
      (%o2) [R_1 = 1000.0 (0.01 tol  + 1),
                                   1
                                          R_2 = 2000.0 (0.01 tol  + 1)]
                                                                2

      (%i3) divider:U_Out=U_In*R_1/(R_1+R_2);
                                      R_1 U_In
      (%o3)                   U_Out = ---------
                                      R_2 + R_1

      (%i4) wc_typicalvalues(vals);
      (%o4)             [R_1 = 1000.0, R_2 = 2000.0]

      (%i5) wc_typicalvalues(subst(vals,divider));
      (%o5)            U_Out = 0.3333333333333333 U_In

Function: wc_inputvalueranges (expression, [num])

  Convenience function: Displays a list which parameter can vary between which values.

  Example:

      (%i1) load("wrstcse")$

      (%i2) vals: [
         R_1= 1000.0*(1+tol[1]*.01),
         R_2= 2000.0*(1+tol[2]*.01)
       ];
      (%o2) [R_1 = 1000.0 (0.01 tol  + 1),
                                   1
                                          R_2 = 2000.0 (0.01 tol  + 1)]
                                                                2

      (%i3) wc_inputvalueranges(vals);
              [ R_1  min = 990.0   typ = 1000.0  max = 1010.0 ]
      (%o3)   [                                               ]
              [ R_2  min = 1980.0  typ = 2000.0  max = 2020.0 ]

Function: wc_systematic (expression, [num])

  Systematically introduces num values per parameter into expression and returns a list of the result. If no num is given, num defaults to 3.

  See also `wc_montecarlo`.

  Example:

      (%i1) load("wrstcse")$

      (%i2) vals: [
         R_1= 1000.0*(1+tol[1]*.01),
         R_2= 2000.0*(1+tol[2]*.01)
       ];
      (%o2) [R_1 = 1000.0 (0.01 tol  + 1),
                                   1
                                          R_2 = 2000.0 (0.01 tol  + 1)]
                                                                2

      (%i3) divider: U_Out=U_In*(R_1)/(R_1+R_2);
                                      R_1 U_In
      (%o3)                   U_Out = ---------
                                      R_2 + R_1

      (%i4) wc_systematic(subst(vals,rhs(divider)));
      (%o4) [0.3333333333333334 U_In, 0.3311036789297659 U_In,
      0.3289036544850498 U_In, 0.3355704697986577 U_In,
      0.3333333333333333 U_In, 0.3311258278145696 U_In,
      0.3377926421404682 U_In, 0.3355481727574751 U_In,
      0.3333333333333333 U_In]

Function: wc_montecarlo (expression, num)

  Introduces num random values per parameter into expression and returns a list of the result.

  See also `wc_systematic`.

  Example:

      (%i1) load("wrstcse")$

      (%i2) vals: [
         R_1= 1000.0*(1+tol[1]*.01),
         R_2= 2000.0*(1+tol[2]*.01)
       ];
      (%o2) [R_1 = 1000.0 (0.01 tol  + 1),
                                   1
                                          R_2 = 2000.0 (0.01 tol  + 1)]
                                                                2

      (%i3) divider: U_Out=U_In*(R_1)/(R_1+R_2);
                                      R_1 U_In
      (%o3)                   U_Out = ---------
                                      R_2 + R_1

      (%i4) wc_montecarlo(subst(vals,rhs(divider)),10);
      (%o4) [0.3365488313167528 U_In, 0.3339089445851889 U_In,
      0.314651402884122 U_In, 0.3447359711624277 U_In,
      0.3294005710066001 U_In, 0.3330897542463686 U_In,
      0.3397591863729343 U_In, 0.3227030530673181 U_In,
      0.3385512773502185 U_In, 0.314764470912582 U_In]

Function: wc_mintypmax (expr, [n])

  Prints the minimum, maximum and typical value of expr. If n is positive, n values for each parameter will be tried systematically. If n is negative, -n random values are used instead. If no n is given, 3 is assumed.

  Example:

      (%i1) load("wrstcse")$
      (%i2) ratprint:false$

      (%i3) vals: [
         R_1= 1000.0*(1+tol[1]*.01),
         R_2= 1000.0*(1+tol[2]*.01)
       ];
      (%o3) [R_1 = 1000.0 (0.01 tol  + 1),
                                   1
                                          R_2 = 1000.0 (0.01 tol  + 1)]
                                                                2

      (%i4) assume(U_In>0);
      (%o4)                      [U_In > 0]

      (%i5) divider:U_Out=U_In*R_1/(R_1+R_2);
                                      R_1 U_In
      (%o5)                   U_Out = ---------
                                      R_2 + R_1

      (%i6) lhs(divider)=wc_mintypmax(subst(vals,rhs(divider)));
      (%o6) U_Out = [min = 0.495 U_In, typ = 0.5 U_In,
                                                      max = 0.505 U_In]

Function: wc_tolappend (list)

  Appends two list of parameters with tolerances renumbering the tolerances of both lists so they don’t coincide.

  Example:

      (%i1) load("wrstcse")$

      (%i2) val_a: [
         R_1= 1000.0*(1+tol[1]*.01),
         R_2= 1000.0*(1+tol[2]*.01)
       ];
      (%o2) [R_1 = 1000.0 (0.01 tol  + 1),
                                   1
                                          R_2 = 1000.0 (0.01 tol  + 1)]
                                                                2

      (%i3) val_b: [
         R_3= 1000.0*(1+tol[1]*.01),
         R_4= 1000.0*(1+tol[2]*.01)
       ];
      (%o3) [R_3 = 1000.0 (0.01 tol  + 1),
                                   1
                                          R_4 = 1000.0 (0.01 tol  + 1)]
                                                                2

      (%i4) wc_tolappend(val_a,val_b);
      (%o4) [R_1 = 1000.0 (0.01 tol  + 1),
                                   2
      R_2 = 1000.0 (0.01 tol  + 1), R_3 = 1000.0 (0.01 tol  + 1),
                            1                             4
      R_4 = 1000.0 (0.01 tol  + 1)]
                            3

Function: wc_mintypmax2tol (tolname, minval, typval, maxval)

  Generates a parameter that uses the tolerance tolname that tolerates between the given values.

  Example:

      (%i1) load("wrstcse")$

      (%i2) V_F: U_Diode=wc_mintypmax2tol(tol[1],.5,.75,.82);
                                                2
      (%o2) U_Diode = (- 0.09000000000000002 tol ) + 0.16 tol  + 0.75
                                                1            1

      (%i3) lhs(V_F)=wc_mintypmax(rhs(V_F));
      (%o3) U_Diode = [min = 0.5, typ = 0.75, max = 0.8199999999999998]