Archive Trac docs calc

Docs Calc

Legacy Trac archive page imported from docs_calc. Source: https://genapp.rocks/wiki/wiki/docs_calc. Review age, links, and examples before treating as current.

calculated fields

• currently in genappalpha rev 1096 or greater

• calculated fields compute values dynamically during user input

• example

        ,{
            "role"       : "input"
            ,"id"         : "m"
            ,"label"      : "mass [kg]"
            ,"type"       : "float"
            ,"required"   : "true"
            ,"help"       : "Enter the mass in kilograms"
        }
        ,{
            "role"       : "input"
            ,"id"         : "c"
            ,"label"      : "Speed of light [m/s]"
            ,"type"       : "float"
            ,"default"    : 299792458
            ,"required"   : "true"
            ,"help"       : "Enter the speed of light in meters/second"
        }
        ,{
            "role"       : "input"
            ,"readonly"  : "true"
            ,"id"         : "E"
            ,"label"     : "Energy [J]"
            ,"type"      : "text"
            ,"calc"      : "m*c^2"
        }

• will dynamically update the field "E" when "m" or "c" are changed based upon the calculation E=m*c^2

notes

• any id or numeric value should be able to be used
• a calculation can be made on a calculated field
  • e.g. we could add to the above example

        ,{
            "role"       : "input"
            ,"readonly"  : "true"
            ,"id"         : "logE"
            ,"label"     : "log Energy [J]"
            ,"type"      : "text"
            ,"calc"      : "log(E)"
        }

• to also get the log of E
• circular references and syntax errors will generate an error at runtime
  • we plan to push this to the generation phase for early checking

currently supported operations

binary operators

• • : addition
• • : subtraction
• • : multiplication
• / : division
• !^ : exponentiation

functions

• abs(x) : absolute value
• acos(x) : arccosine
• asin(x) : arcsine
• atan(x) : arctangent
• atan2(y,x) : tangent of y over x
• ceil(x) : integer round up
• cos(x) : cosine
• exp(x) : e to the power of x
• floor(x) : integer round down
• log(x) : natural log
• max(x,y,...) : maximum
• min(x,y,,..) : minimum
• pow(x,y) : raise x to the y power
• random() : random # between 0 & 1
• round(x) : round to nearest integer
• sin(x) : sine
• sqrt(x) : square root
• tan(x) : tangent

repeaters and calc

• calculated fields can be used under repeaters (genappalpha rev >= 1112)
• id's will be taken from the top level (not under a repeater) if they exist
• if the id does not exist at the top level, the one from the same level will be used.
  • e.g. this will provide a separate calculation for each repeater count

{
    "role"       : "input"
    ,"id"         : "ir1"
    ,"label"      : "do calcs"
    ,"type"       : "integer"
    ,"repeater"   : "true"
}
,{
    "role"       : "input"
    ,"id"         : "m"
    ,"label"      : "mass [kg]"
    ,"type"       : "float"
    ,"required"   : "true"
    ,"help"       : "Enter the mass in kilograms"
    ,"repeat"     : "ir1"
}
,{
    "role"       : "input"
    ,"id"         : "c"
    ,"label"      : "Speed of light [m/s]"
    ,"type"       : "float"
    ,"default"    : 299792458
    ,"required"   : "true"
    ,"help"       : "Enter the speed of light in meters/second"
    ,"repeat"     : "ir1"
}
,{
    "role"       : "input"
    ,"readonly"  : "true"
    ,"id"         : "e"
    ,"label"     : "Energy [J]"
    ,"type"      : "text"
    ,"calc"      : "m*c^2"
    ,"repeat"     : "ir1"
}

• and this will also work

{
    "role"       : "input"
    ,"id"         : "c"
    ,"label"      : "Speed of light [m/s]"
    ,"type"       : "float"
    ,"default"    : 299792458
    ,"required"   : "true"
    ,"help"       : "Enter the speed of light in meters/second"
}
,{
    "role"       : "input"
    ,"id"         : "ir1"
    ,"label"      : "do calcs"
    ,"type"       : "integer"
    ,"repeater"   : "true"
}
,{
    "role"       : "input"
    ,"id"         : "m"
    ,"label"      : "mass [kg]"
    ,"type"       : "float"
    ,"required"   : "true"
    ,"help"       : "Enter the mass in kilograms"
    ,"repeat"     : "ir1"
}
,{
    "role"       : "input"
    ,"readonly"  : "true"
    ,"id"         : "e"
    ,"label"     : "Energy [J]"
    ,"type"      : "text"
    ,"calc"      : "m*c^2"
    ,"repeat"     : "ir1"
}

• you can not currently mix id's under different repeaters or repeater levels
• if you have a structure that you would like supported, please get in touch