documentation: Show the correct index for constants and equations

For constant and equations menus, match the index in the help file.

Fixes: #1039
Fixes: #1048

Signed-off-by: Christophe de Dinechin <christophe@dinechin.org>

doc/calc-help/constants.md

@@ -4,7 +4,7 @@ The DB48X calculator features a library of constants covering mathematics,
 physics, chemistry and computer science. The built-in constants can be extended
 using the `config/constants.csv` configuration file.
 
-## Mathematical constants
+## Mathematics constants
 
 ### π constant
 
@@ -345,26 +345,26 @@ logarithmic quantity, most often expressed in decibels dB. I0 is the sound
 intensity used as a reference, corresponding to 0dB.
 
 
-## Dates
+## Dates Constants
 
-### BastilleDay
+### BastilleDay constant
 
 French national day
 
-### MartinLutherKingDeath
+### MartinLutherKingDeath constant
 
 Martin Luther King Jr., an African-American clergyman and civil rights movement
 leader, was fatally shot at the Lorraine Motel in Memphis, Tennessee, on April
 4, 1968, at 6:01 p.m.
 
-### IndependenceDay
+### IndependenceDay constant
 
 Independence Day, known colloquially as the Fourth of July, is a federal holiday
 in the United States which commemorates the ratification of the Declaration of
 Independence by the Second Continental Congress on July 4, 1776, establishing
 the United States of America.
 
-## Computing-related constants
+## Computing constants
 
 ### No constant
 

doc/calc-help/equations.md

@@ -42,6 +42,12 @@ relative to the loads.
 * Internal bending moment is positive counterclockwise on the left-hand part.
 * Shear force is positive downward on the left-hand part.
 
+### Elastic Buckling
+
+These equations apply to a slender column (`K·L/r>100`) with length factor `K`.
+
+![Elastic Buckling](img/ElasticBuckling.bmp)
+
 
 
 ## Electricity

help/db48x.md

@@ -4564,7 +4564,7 @@ The DB48X calculator features a library of constants covering mathematics,
 physics, chemistry and computer science. The built-in constants can be extended
 using the `config/constants.csv` configuration file.
 
-## Mathematical constants
+## Mathematics constants
 
 ### π constant
 
@@ -4905,26 +4905,26 @@ logarithmic quantity, most often expressed in decibels dB. I0 is the sound
 intensity used as a reference, corresponding to 0dB.
 
 
-## Dates
+## Dates Constants
 
-### BastilleDay
+### BastilleDay constant
 
 French national day
 
-### MartinLutherKingDeath
+### MartinLutherKingDeath constant
 
 Martin Luther King Jr., an African-American clergyman and civil rights movement
 leader, was fatally shot at the Lorraine Motel in Memphis, Tennessee, on April
 4, 1968, at 6:01 p.m.
 
-### IndependenceDay
+### IndependenceDay constant
 
 Independence Day, known colloquially as the Fourth of July, is a federal holiday
 in the United States which commemorates the ratification of the Declaration of
 Independence by the Second Continental Congress on July 4, 1776, establishing
 the United States of America.
 
-## Computing-related constants
+## Computing constants
 
 ### No constant
 
@@ -4997,6 +4997,12 @@ relative to the loads.
 * Internal bending moment is positive counterclockwise on the left-hand part.
 * Shear force is positive downward on the left-hand part.
 
+### Elastic Buckling
+
+These equations apply to a slender column (`K·L/r>100`) with length factor `K`.
+
+![Elastic Buckling](img/ElasticBuckling.bmp)
+
 
 
 ## Electricity

help/db50x.md

@@ -4564,7 +4564,7 @@ The DB50X calculator features a library of constants covering mathematics,
 physics, chemistry and computer science. The built-in constants can be extended
 using the `config/constants.csv` configuration file.
 
-## Mathematical constants
+## Mathematics constants
 
 ### π constant
 
@@ -4905,26 +4905,26 @@ logarithmic quantity, most often expressed in decibels dB. I0 is the sound
 intensity used as a reference, corresponding to 0dB.
 
 
-## Dates
+## Dates Constants
 
-### BastilleDay
+### BastilleDay constant
 
 French national day
 
-### MartinLutherKingDeath
+### MartinLutherKingDeath constant
 
 Martin Luther King Jr., an African-American clergyman and civil rights movement
 leader, was fatally shot at the Lorraine Motel in Memphis, Tennessee, on April
 4, 1968, at 6:01 p.m.
 
-### IndependenceDay
+### IndependenceDay constant
 
 Independence Day, known colloquially as the Fourth of July, is a federal holiday
 in the United States which commemorates the ratification of the Declaration of
 Independence by the Second Continental Congress on July 4, 1776, establishing
 the United States of America.
 
-## Computing-related constants
+## Computing constants
 
 ### No constant
 
@@ -4997,6 +4997,12 @@ relative to the loads.
 * Internal bending moment is positive counterclockwise on the left-hand part.
 * Shear force is positive downward on the left-hand part.
 
+### Elastic Buckling
+
+These equations apply to a slender column (`K·L/r>100`) with length factor `K`.
+
+![Elastic Buckling](img/ElasticBuckling.bmp)
+
 
 
 ## Electricity

src/constants.cc

@@ -276,7 +276,7 @@ static const cstring basic_constants[] =
     // ------------------------------------------------------------------------
     // MATH CONSTANTS MENU
     // ------------------------------------------------------------------------
-    "Math",   nullptr,
+    "Mathematics",   nullptr,
 
     "π",        "3.14159",              // Evaluated specially (decimal-pi.h)
     "e",        "2.71828",              // Evaluated specially (decimal-e.h)
@@ -289,7 +289,7 @@ static const cstring basic_constants[] =
     //   Chemistry
     // ------------------------------------------------------------------------
 
-    "Chem",     nullptr,
+    "Chemistry",     nullptr,
 
     "NA",       "6.0221367E23_mol⁻¹",   // Avogradro's number
     "k",        "1.380658E-23_J/K",     // Boltzmann
@@ -303,7 +303,7 @@ static const cstring basic_constants[] =
     //   Physics
     // ------------------------------------------------------------------------
 
-    "Phys",     nullptr,
+    "Physics",     nullptr,
 
     "ⅉ",        "0+ⅈ1",                 // Imaginary unit in physics
     "c",        "299792458_m/s",        // Speed of light
@@ -342,7 +342,7 @@ static const cstring basic_constants[] =
     // ------------------------------------------------------------------------
     //  Computing
     // ------------------------------------------------------------------------
-    "Comp",   nullptr,
+    "Computing",   nullptr,
 
     "No",                       "False",                // No value = false
     "Yes",                      "True",                 // Yes value = true

src/equations.cc

@@ -72,7 +72,6 @@ static const cstring basic_equations[] =
 
     "RelativityMassEnergy",             "'(E_J)=(m_kg)*Ⓒc^2'",
     "IdealGas",                         "'(P_Pa)*(V_m^3)=(n_mol)*ⒸR*(T_K)'"
-
 };
 //   clang-format on
 
@@ -110,8 +109,8 @@ const equation::config equation::equations =
 //  Define the configuration for the equations
 // ----------------------------------------------------------------------------
 {
-    .menu_help      = "Equations",
-    .help           = "Equation",
+    .menu_help      = "",
+    .help           = "",
     .prefix         = L'Ⓔ',
     .type           = ID_equation,
     .first_menu     = ID_EquationsMenu00,