'synchronize' cell values dependent on each other in google spreadsheet - google-sheets

Question

Suppose I have three cells, one containing the distance, one the speed and the other the time. Now I want to be able to fill in two cells (e.g. distance and speed) and have the time calculated in the third cell. But when I fill in the speed and the time, the distance should be calculated.
How can this be achieved in google spreadsheets? I suppose there should be some kind of check to not create an infinite loop. I tried to search for cell synchronization or cell dependency, but I think this is not the right term for this problem.

Answer 1

You can do this with a nested if statement:
=if(And(isnumber(A2),isnumber(C2)),ROUND(A2/C2),if(And(isnumber(A2),isnumber(B2)),round(A2/B2),if(and(isnumber(B2),isnumber(C2)),B2*TIMEVALUE(C2)*24,)))
Here is a screenshot for all three scenarios:

Answer 2

You may use OnEdit event:
user enters some value (speed, row, distance)
script checks for other values,
calculates the result
paste the result into cells
The whole text of script is here:
function onEdit(t) {
var workSheetName = 'Sheet1'; // change sheet name to yours
var distanceRangeAddress = 'A2:A'; // change if needed
var speedRangeAddress = 'B2:B'; // change if needed
var timeRangeAddress = 'C2:C'; // change if needed
var ss = SpreadsheetApp.getActiveSheet();
var sn = ss.getName();
var distance, speed, time;
if (sn == workSheetName) {
var tr = t.range;
if (t.oldValue != tr.getValue() && tr.getNumColumns() == 1 && tr.getNumRows() == 1) {
// distance
var myr = ss.getRange(distanceRangeAddress);
if (RangeIntersect(tr, myr)) {
distance = tr.getValue();
speed = tr.offset(0, 1).getValue();
time = tr.offset(0, 2).getValue();
if (time > 0) {
speed = distance / time;
tr.offset(0, 1).setValue(time);
return;
}
if (speed > 0) {
time = distance / speed;
tr.offset(0, 2).setValue(time);
return;
}
}
// speed
myr = ss.getRange(speedRangeAddress);
if (RangeIntersect(tr, myr)) {
speed = tr.getValue();
distance = tr.offset(0, -1).getValue();
time = tr.offset(0, 1).getValue();
if (time > 0) {
distance = speed * time;
tr.offset(0, -1).setValue(distance);
return;
}
if (distance > 0) {
time = distance / speed;
tr.offset(0, 1).setValue(time);
return;
}
}
// time
myr = ss.getRange(timeRangeAddress);
if (RangeIntersect(tr, myr)) {
time = tr.getValue();
distance = tr.offset(0, -2).getValue();
speed = tr.offset(0, -1).getValue();
if (speed > 0) {
distance = speed * time;
tr.offset(0, -2).setValue(distance);
return;
}
if (distance > 0) {
speed = distance / time;
tr.offset(0, -1).setValue(speed);
return;
}
}
}
}
}
function RangeIntersect(R1, R2) {
var LR1 = R1.getLastRow();
var Ro2 = R2.getRow();
if (LR1 < Ro2) return false;
var LR2 = R2.getLastRow();
var Ro1 = R1.getRow();
if (LR2 < Ro1) return false;
var LC1 = R1.getLastColumn();
var C2 = R2.getColumn();
if (LC1 < C2) return false;
var LC2 = R2.getLastColumn();
var C1 = R1.getColumn();
if (LC2 < C1) return false;
return true;
}
You may want to change parametres in the beginning of the script:
var workSheetName = 'Sheet1'; // change sheet name to yours
var distanceRangeAddress = 'A2:A'; // change if needed
var speedRangeAddress = 'B2:B'; // change if needed
var timeRangeAddress = 'C2:C'; // change if needed
Here's example file.
The script could be improved and adopted to your needs. Please, look for more information here.