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====== Math 445 lecture diary: if-elseif-else ====== Today we'll look at slightly more complex functions, with * multiple arguments * multiple return values * ''if-elseif-else'' statements * ''switch'' statements ====Multiple arguments and return values==== The declaration of a function ''f'' with multiple arguments and multiple return values has general form <code matlab> function [rtn1, rtn2, rtn3, ...] = f(arg1, arg2, arg3, ...) </code> ====if-elseif-else statement==== The general form of an ''if-elseif-else'' statement is <code matlab> if condition1 action1 elseif condition2 action2 elseif condition3 action3 else action4 end </code> though of course you can have as many ''elseif'' statements as you like. ====Example: if-elseif-else and multiple args and return val==== Write a Matlab function ''temp2kcf'' converts a temperature ''t'' in any one of the three units Kelvin, Celsius, or Farenheit, and returns the temperature in all three units. The function should have two arguments, the temperature ''t'' and a character ''units'' which specifies the units as either K, C, or F and three return values, ''tK, tC, tF''. <code matlab> function [tK, tC, tF] = temp2kcf(t, units); % convert temperature t in units 'C', 'F', or 'K' to all three of those units % convert input temp to Kelvin if units == 'F' tK = 5/9*t + 255.37; elseif units == 'C' tK = t + 273.15; elseif units == 'K' tK = t; else fprintf('error: unknown units %c, returning absolute zero\n', units); tK = 0; end % convert Kelvin to output temps tC = tK - 273.15; tF = 9/5*tC + 32; end ====switch statement==== The above problem is actually better done with a switch statement. Switch statements perform conditional execution based on the value of a variable or an expression. The general form is <code matlab> switch expression case value1 action1 case value2 action2 case value3 action3 otherwise action4 end </code>
